SIM983 - Unspecified SRS - Free user manual and instructions

USER MANUAL SIM983 SRS

Revision2.3• January4,2016

Certification

StanfordResearchSystemscertifiesthatthisproductmetitspublishedspecificationsatthetime ofshipment.

Warranty

ThisStanfordResearchSystemsproductiswarrantedagainstdefectsinmaterialsandworkmanshipforaperiodofone(1)yearfromthedateofshipment.

Service

Forwarrantyserviceorrepair, thisproductmustbereturnedtoaStanfordResearchSystems authorizedservicefacility.ContactStanfordResearchSystemsoranauthorizedrepresentative beforereturningthisproductforrepair.

Informationinthisdocumentissubjecttochangewithoutnotice.

Copyright © StanfordResearchSystems, Inc., 2005–2016. All rights reserved.

StanfordResearchSystems, Inc.

1290-DReamwoodAvenue

Sunnyvale, CA94089USA

Phone:[phone]• Fax:[phone]

www.thinkSRS.com• e-mail:[e-mail]

PrintedinU.S.A.Documentnumber9-01598-903

Contents

GeneralInformationiii

SafetyandPreparationforUse......iii

Symbols......iv

Notation......v

Specifications......vi

1GettingStarted1-1

1.1 Introduction to the Instrument......1-2
1.2Front-PanelOperation....1-3
1.3Connections....1-5
1.4 Power-On 1-6
1.5RestoringtheDefaultConfiguration...... 1-6
1.6SIMInterface....1-7

2DescriptionofOperation

2.1 Signal Connections and Grounding ..... 2-2
2.2Autocalibration.... 2-2
2.3ACCharacteristics....2-3
2.4 Clock Stopping 2-4

3RemoteOperation

3.1IndexofCommonCommands.... 3-2
3.2 Alphabetic List of Commands 3-4
3.3 Introduction 3-6
3.4 Commands 3-7
3.5 Status Model 3-19

4PerformanceVerification

4.1 Verifying the DC Accuracy ..... 4-2
4.2 Verifying AC Performance.... 4-4
4.3 Noise Characteristics 4-6
4.4 Performance Test Record 4-8

5CircuitDescription

5.1 Circuit Discussion 5-2
5.2 Parts List 5-6
5.3 Schematic Diagrams 5-10

AIndexA-1

General Information

TheSIM983ScalingAmplifier, part of Stanford Research Systems' Small Instrumentation Modules family, perform the function

$$ V _ {\text { out }} = G \times (V _ {\mathrm{in}} + V _ {\mathrm{ofs}}) $$

where V_in and V_out are voltages (upto±10V) at the input and the output of the instrument, respectively, Gisauser-specified gain, and V_ofs is a user-specified offset voltage. The instrument is accurate within its resolution.

Safety and Preparation for Use

Thefront-panelinput, front-paneloutput, and therear-paneloutput coaxial(BNC) connectors in the SIM983 are referenced to the Earth, and their outercasings are grounded. Nodangerous voltages are generated by themodule.

CAUTION

Do not exceed ±15 volts to the Earth at the center terminal of each BNC connector. Donotinstallsubstitutepartsorperformunauthorized modificationstothisinstrument.

TheSIM983isasingle-widemodule designed to be used inside the SIM900Mainframe. Donotturnonthepower to themainframe or apply voltage input to the module until the module is completely inserted into themainframe and locked in place.

Symbols you may Find on SRS Products

Symbol Description
	Alternating current
	Caution - risk of electric shock
	Frame or chassis terminal
	Caution - refer to accompanying documents
	Earth (ground) terminal
	Battery
	Fuse
	On (supply)
	Off (supply)

Notation

WARNING

CAUTION

The following notation will be used throughout this manual:

A warning mean that injury or death is possible if the instructions are not obeyed.

Acautionmeansthatdamagetotheinstrumentorotherequipment is possible.

Typesetting conventions used in this manual are:

• Front-panelbuttonsaresetas[gain]; [gain]isshorthandfor"[gain]&[gain]".
  • Front-panelindicatorsaresetasOVLD.
  • Signalnamesaresetas-STATUS.
  • SignallevelsaresetasHIGH.
• Remotecommandnamesaresetas*IDN?.
• Literaltextotherthancommandnamesissetas0FF.
  • SpecialASCII charactersaresetas⟨CR⟩.

Remotecommandexampleswillallbesetinmonospacedfont. In these examples, datasentbythehostcomputertotheSIM983areset asstraightteletypefont, whileresponsesreceivedbythehost computerfromtheSIM983aresetasslantedteletypefont.

Specifications

Performance characteristics

Input	Voltage [1]	MinTyp	MaxUnits
		-10.0		+10.0	V
	CouplingDC
	Resistance0	991.001.01	MΩ
	Capacitance2	6pF
	Biascurrent[2]40	pA
	Voltagenoise[3,4],1kHz43nV/
	10kHz38nV/
	Currentnoise,10kHz		3		fA/
	Terminals	GroundedBNC[5]
Gain	Absolutevalue0.01		19.99
	Polarity	Inverting,non-inverting
	Resolution	0.01
	Accuracy[2]±0.01
	Stability			±10	ppm/°C
Offset[3]	Voltage	-10.00		+10.00	V
	Resolution, |V_ofs| ≤ 1.999 V	1			mV
	|V_ofs| ≥ 2.00 V10mV
	Accuracy [2,4,6]	±1 ± 200			mV + ppm
	Stability [4]			±20 ± 20	( V + ppm)/^
	Settlingtime[7]			2	s
AC performance	-3 dB bandwidth, |G| ≤ 1.00	2.0			MHz
	Gain-bandwidth product, |G| ≥ 1.00	3.0			MHz
	[8] |G| ≥ 2.40	5.0			MHz
	|G| ≥ 4.20	10.0			MHz
	|G| ≥ 9.60	17.0			MHz
	Slewrate70V/μs
	THD,1kHz			-90	dB
Output	Voltage [1]	-10.0		+10.0	V
	Maximumcurrent	±100			mA
	Shortcircuit duration	Indefinite
	Resistance50Ω
	Terminals	Grounded BNC, front [5] and rear [9]
Operating	Temperature [10]	0		40	°C
	Power	+5, ±15			V DC
	Supply current, +5 V		100		mA
	±15V		300		mA

Conditions:

[1] Anoverload will be detected and the instrument is not guaranteed to perform properly if these limits are exceeded, or if V_in + V_ofs exceeds the limits. Continuous application of an input voltage V_in in excess of ± 15V will damage the instrument.

[2]At23 °C.

[3]Referredtoinput.

[4]For|G| ≥ 2.

[5]Amphenol31-10-4052orsimilar.

[6]Followinganautocalibrationat(23±5) °Cwithin24hours;following a2-hourwarmup.

[7]Towithin0.1%ofthefinalvalue.

[8]Thegain-bandwidthproduct(GBP)determinesthe-3dBbandwidth: For gain G, the bandwidth is GBP/|G|.

[9]Tyco227169-4orsimilar.

[10]Non-condensing.

Generalcharacteristics

InterfaceSerial(RS-232)throughSIMinterface

ConnectorsBNC(2front[5],1rear[9]);DB-15(male)SIMinterface

Weight1.5lbs

Dimensions1.5 "W× 3.6 H× 7.0 D

1 Getting Started

Thischaptergivesyouthenecessaryinformationtogetstarted quicklywithyourSIM983ScalingAmplifier.

In This Chapter

1.1 Introduction to the Instrument......1-2

1.1.1 Frontandrearpanels......1–3

1.2Front-PanelOperation....1-3

1.2.1Polarity....1-3

1.2.2Gain....1-3

1.2.3Offset....1-4

1.2.4Overload....1-4

1.3Connections....1-5

1.4Power-On....1-6

1.5RestoringtheDefaultConfiguration .....1-6

1.6SIMInterface 1-7

1.6.1SIMinterfaceconnector......1-7

1.6.2 Directinterfacing......1–7

1.1 Introduction to the Instrument

TheSIM983ScalingAmplifierprovidesfineadjustablegainand offset control of an analog signal. The gain (0.01 ≤ |G| ≤ 19.99) , itspolarity(invertingornon-inverting), and the offset voltage (-10.00V ≤ V_ofs ≤ +10.00V) can be set from either the front panel or remotely. A remote computer can access the module through the SIM900Mainframe, using RS-232orGPIB.

ThedigitalcontrolcircuitryintheSIM983 is designed with aspecial clock-stopping architecture. Themicrocontrolleristurnedononly whenthepolarity, gain, or offset are being changed, during remote communications, or when an overload condition occurs. This guar- anteesthatnodigitalnoisecontaminateslow-levelanalogsignals.

DC accuracy A user-commanded autocalibration procedure allows one to control theinput-referredoffsettowithin±1mVofthedesiredvalue.

The amplifier's high slew rate allows it to output a ±10 V peak-peak sine wave at a frequency of 1 MHz. The gain stage of the amplifier is compensated in a flexible fashion to provide an sensible pulsere-sponse, so the bandwidth of the instrument is adjusted according to its gain. ^1 The ample output current in the SIM983 permit soneto drive a 50Ω load.

If the maximum input voltage is exceeded, or the gain or offset cause the output voltage to exceed its maximum, the appropriate overload LEDturnson. If armed, themodulealsogeneratesastatussignalto alert the user of the overload condition. The SIM983 can be operated outsidetheSIM900MainframebypoweringitwithitsrequiredDC voltages.

AblockdiagramoftheamplifierisshownbelowinFigure 1.1.

graph TD
    A["Input BNC"] --> B["1.00 MΩ"]
    B --> C["High-impedance buffer"]
    C --> D["Programmable offset"]
    D --> E["Invert"]
    E --> F["non-inverting polarity"]
    F --> G["Programmable gain (inverting)"]
    G --> H["37 Ω"]
    H --> I["Output BNC, rear"]
    G --> J["13 Ω"]
    G --> K["13 Ω"]
    L["Programmable gain (inverting)"] --> M["frequency compensation"]
    M --> N["Inverting polarity"]
    N --> O["Inverting polarity"]
    O --> P["Inverting polarity"]
    P --> Q["Inverting polarity"]
    Q --> R["Inverting polarity"]
    R --> S["Inverting polarity"]
    S --> T["Inverting polarity"]
    T --> U["Inverting polarity"]
    U --> V["Output BNC, front"]

Figure 1.1:TheSIM983blockdiagram.

1.1.1 Front and rear panels

VSRS SIM983 Scaling Amplifier Gain 15.75 Input Offset -.090 polarity gain offset INPUT OVLD 1 MΩ OUTPUT OVLD ±10 V SIM983 SCALING AMP OUTPUT S/N VSRS MADE IN U.S.A.

Figure1.2:TheSIM983frontandrearpanels.

1.2 Front-Panel Operation

1.2.1 Polarity

Thepolarityisthesignofthegain.Itisindicatedontheupperdisplay ofthefrontpanel.Tochangethepolarity,pressthe[polarity]button once.Holdingthisbuttonhasnoeffect.

Pressing[polarity]hasnoeffectontheinput-referredoffset.However,asimultaneous pressof[polarity]andoneof[gain]hasa specialmeaning.Thispressinitiatesautocalibration(Section2.2).

1.2.2 Gain

ThegainGcanbesettoanabsolutevaluebetween0.01and19.99.To raiseorlowertheabsolutevalueofthegain,pressthebutton[gain] orthebutton[gain]. Thedecimalpointpositionofthegaindisplayedonthefrontpanelisfixed,sotheresolutionofthegainis0.01. If [gain 1] is pressed when the gain G = ± 19.99 , the press has no effect. If [gain 7] is pressed when G = ± 0.01 , the press has no effect. Pressing either [gain] does not change the polarity.

Ifoneof[gain]ispressedandheld, thegainiscontinuouslyadjusted. Therateoftheadjustmentincreasesasthebuttonisheld. If theabsolutevalueofthegainisbeinglowered, therateoftheadjustment changes as |G| crosses 1.00, and possibly again as |G| crosses 0.10.

resetting gain

If both [gain ▲] and [gain ▼] buttons are pressed at the same time, the absolute value of the gain is reset to 1.00. This action does not change the polarity.

Pressingoneof[gain]and[polarity]atthesametimehasaspecial meaning. Thispressinitiatesautocalibration(Section2.2).

1.2.3 Offset

The input-referred voltage offset V_ofs can be set to a value between -10.00 V and +10.00 V. Its value, in volts, is shown on these second line of display on the front panel of the amplifier.

To increase or decrease the offset, press the button [offset ▲] or the button [offset ▼]. Unlike the gain, the “up” and “down” buttons adjust the offset, not its absolute value. Thus, for example, pressing [offset ▲] when V_ofs = -5.49V makes V_ofs = -5.48V . If [offset ▲] is pressed when V_ofs = +10.00V , the press has no effect. If [offset ▼] is pressed when V_ofs = -10.00V , the press has no effect.

Between the values -2.00V < V_ofs < +2.00V , the offset is selected with 0.001V resolution; the position of the decimal point on the front-panel display is shifted to the left. Although the resolution is 0.01V for |V_ofs| ≥ 2.00V , the accuracy of the offset is still ± 1mV ± 0.02% . Thus, for example, setting V_ofs = -5.48V produces V_ofs = (-5.480 ± 0.001 ± 0.001) = (-5.480 ± 0.002)V .

If one of [offset ▲] is pressed and held, the offset is continuously adjusted. Therateoftheadjustmentincreasesasthebuttonisheld. If the valuecrossesthethreshold V_ofs = ± 2.00 V , the rate changes appropriately.

resetting offset

If both [offset ▲] and [offset ▼] buttons are pressed at the same time, the offset is reset to 0.000 V.

1.2.4 Overload

There are two overload indicators, one OVLD LED in the INPUTblockandoneOVLD LEDintheOUTPUTblockofthefront panel. The overload signal can also be asserted on the STATUS pin. SeeSection3.5.

1.2.4.1 Input overload

AnoverloadconditionisrecognizedandtheinputOVLDLEDis activatediftheabsolutevalueofthevoltageappliedtotheinput overload limits exceeds certain limits. These limits are typically ±10.0 V, and are between

$$ - 1 0. 4 \mathrm{V} \leq V _ {\min} \leq - 9. 9 \mathrm{V}, 9. 9 \mathrm{V} \leq V _ {\max} \leq 1 0. 4 \mathrm{V}. $$

Theoverloadedstateisalsorecognized,andtheinputoverloadLED activated,ifthesumoftheinputvoltageandthecommandedoffset, |V_in+V_ofs| , exceeds these limits. To distinguish between the two input overloadpossibilities,usethecommandOVLD? .TheoverloadLED staysonforaminimumof50ms; afterthistimeitturnsoffithe overloadconditionhasceased.

1.2.4.2 Output overload

AnoverloadconditionisrecognizedandtheoutputOVLD LEDis activated if the absolute value |G × (V_in + V_ofs)| exceeds the limits in Section 1.2.4.1. The overload LED stays on for a minimum of 50 ms; afterthistimeitturnsoffiftheoverloadconditionhasceased.

1.3 Connections

For a discussion of the front and rear BNC connections, see Section2.1.TheSIMinterfaceconnectorisdiscussedinSection1.6.1.

1.4 Power-On

The instrument retains the values of the gain and the offset inn non-volatile memory. Upon power-on, those settings are restored to their values before the power was turned off.

The power-on configuration of theremote interface is detailed in Section 3.3.1.

1.5 Restoring the Default Configuration

The default configuration of the SIM983 is G = +1.00 , V_ofs = 0.000V , and bandwidth@(seeSection2.3.1). This configuration is reached from theremote interface by issuing the *RST command. To reset only the gain the offset to their default values, use button combinations described in Sections 1.2.2 or 1.2.3.

1.6 SIM Interface

The primary connection to the SIM983 Scaling Amplifier is therear-panel DB-15 SIM interface connector. Typically, the SIM983 is mated to a SIM900 Mainframe viathis connection, either throughout one of the internal mainframeslots or theremotecable interface.

ItisalsopossibletooperatetheSIM983directly, without using the SIM900Mainframe. Thissectionprovidesdetailsontheinterface.

1.6.1 SIM interface connector

TheDB-15SIMinterfaceconnectorcarriesallthepowerandcommunicationlinestotheinstrument.Theconnectorsignalsarespecified inTable1.1.

Pin	SignalSrc	DestDescription	Direction
1	S	IGNALGNDMF	SIM GroundReference1
2	-STATUS		SIM MF	Status/service request (GND = asserted, +5 V= idle)
3	RTS		MF SIM	HW handshake (unused in SIM983)
4	CTS		SIM MF	HW handshake (unused in SIM983)
5	-REF_10MHZ		MF SIM	10 MHz reference (no connection in SIM983)
6	-5V		MF SIM	Power supply (no connection in SIM983)
7	-15V		MF SIM	Power supply
8	PSRTN	MF SIM GroundReference2
9	CHASSISGND Chassisground
10	TXD	MF SIM	Async data (start bit = “0”= +5 V; “1”= GND)
11	RXD	SIM MF	Async data (start bit = “0”= +5 V; “1”= GND)
12	+REF_10MHZ	MF SIM	10 MHz reference (no connection in SIM983)
13	+5V	MF SIM	Power supply
14	+15V	MF SIM	Power supply
15	+24V	MF SIM	Power supply (no connection in SIM983)

Table1.1: SIMinterfaceconnectorpinassignments,DB-15.

1.6.2 Direct interfacing

TheSIM983isintendedforoperationintheSIM900Mainframe, but usersmaywishtodirectlyinterfacethemoduletotheirownsystems withouttheuseofadditionalhardware.

ThematingconnectorneededisastandardDB-15receptacle,such asTycopartnumber747909-2(orequivalent).Clean,well-regulated supply voltages of ± 15.0V DC, +5.0V DC must be provided, followingthepinoutspecified inTable1.1 andtheminimumcurrentsin thetableonPagevi.GroundmustbeprovidedonPins1and8,with chassis ground on Pin 9. The STATUS signal may be monitored

CAUTION

onPin2foralow-goingTTL-compatibleoutputindicatingastatus message.SeeSection3.5forthedescriptionofstatusmessages.

The SIM983 has nointernal protection against reverse polarity, missing supply, or overvoltage on the +5 V and the ±15 V power-supply pins. Supply voltages above 5.5 V on Pin 13, above +16 V on Pin 14, or below -16 V on Pin7 are likely todamagethe instrument. SRS recommends using the SIM983 together with the SIM900 Mainframe form most applications.

1.6.2.1 Direct interface cabling

If the user intend stodirectly wire the SIM983 independent of the SIM900 Mainframe, communication is usually possible by directly connecting the appropriate interfacelines from the SIM983 DB-15 plug to the RS-232 serial port of a personal computer. ^2 Connect RXD from the SIM983 directly to R Don the PC, TX D directly to TD, and similarly RTS→RT Sand CTS→CTS. In other words, anull-modem-styleable is not needed.

TointerfacedirectlytotheDB-9male(DTE)RS-232porttypically foundoncontemporarypersonalcomputers,acablemustbemade withafemaleDB-15sockettomatewiththeSIM983,andafemale DB-9sockettomatewiththePC'sserialport.Separateleadsfrom theDB-15needtogotothepowersupply,makingwhatissometimes knowasa"hydra"cable.ThepinconnectionsaregiveninTable1.2.

DB-15/FtoSIM983Name

	DB-9/F
10←→	3	TxD
11←→	2	RxD
	5	ComputerGround
	toPowerSupply
7←→	-15VDC
13←→	+5 V DC
14←→	+15 V DC
1←→	Ground 1 (separate wire to Ground)
8←→	Ground 2 (separate wire to Ground)
9←→	Chassis Ground (separate wire to Ground)

Table1.2:SIM983directinterfacecablepinassignments.

note about grounds The distinct Ground References 1 and 2, and the chassis ground, are not directly connected within the SIM983. Ground1carriesthereturn

currentsofdigitalcontrolsignalsandthepowersupplies,whereas theinputvoltageandtheoutputvoltagereferencetoGround2(Section2.1.2).WhenoperatingintheSIM900,thethreegroundsare tiedtogetherintheSIM900Mainframe.Grounds1and2areconnectedthroughback-to-backSchottkydiodes,sotheycannotbemore than ±0.35 V apart. The three ground lines should be separately wiredtoasingle,low-impedancegroundsourceatthepowersupply.

1.6.2.2 Serial settings

The initial serial port settings at power-on are: baud rate 9600, 8 bits, n parity, 1 stop bit, and no flow control. The baud rate of the SIM 983 cannot be changed. Flow control is not implemented in the SIM 983. The parity may be changed with the PARI command.

2 Description of Operation

Thischapterprovidesanumberofadditionaldetailsoftheoperation oftheSIM983.

In This Chapter

2.1SignalConnectionsandGrounding......2-2

2.1.1 Outputdrive....2-2

2.1.2 Grounds....2-2

2.2Autocalibration....2-2

2.3ACCharacteristics....2-3

2.3.1 Bandwidth....2-3

2.3.2Slewrate....2-3

2.4ClockStopping......2-4

2.1 Signal Connections and Grounding

2.1.1 Output drive

The output impedance of the SIM983 Scaling Amplifier is 50Ω. The amplifier and drivelo load impedances from ∞ to 50Ω for the full ±10V range of output voltage. When driving a 50Ω load, the gain will be half of that displayed on the front panel.

Therear-paneloutputconnectoriswiredinparallelwiththefrontpaneloutput, and share some of the output impedance (Figure 1.1). The output stage is not designed to drivetwo 50 loadssimultaneously.

2.1.2 Grounds

Both the input and the output of the SIM983 are referenced to ground. Tomaintain the DC accuracy of the instrument, there are two separate ground references. Ground1 (Pin1 of the SIM interface connector) provides a return path for digital control signals and the power supply currents, while Ground2 (Pin8 of the interface connector) serves as there reference point for analog voltages. The outercasings of the input and the output front-panel BNC connectors are tied to Ground2. The output current of the amplifier return to the power supply through Ground2.

The outercasing of therear-panel output BNC is connected to chassis ground, Pin9 of the DB-15 SIM interface connector. These separate power, analog, and chassis grounds are not directly connected within the amplifier. When operating in the SIM 900 Mainframe, the three grounds are tied together inside them mainframe, and through them in frameto the Earth. Grounds 1 and 2 are connected inside the SIM 983 through back-to-back Schottky diodes, so they cannot be more than ±0.35 V apart.

2.2 Autocalibration

ToensureDCoffsetaccuracy, theamplifiermustbeself-calibrated within the 24 hours preceding a measurement. A valid autocalibrationmusttakeplaceat(23±5) °C with themodulewarmedup for at least 2 hours at (23±5) °C. If the module is being used inside the SIM900Mainframe, theautocalibration must also be inside themainframe. Otherwise, perform theautocalibration with the same connection to an independent supply as you use for the operation. Theautocalibration is only accurate if the output has stabilized within ±15 mV of zero for at least 2 minutes immediately preceding the calibration. However, the gain and the offset need not be at

theirdefaultvalues;afterthecalibrationcompletes,thesevaluesare restored.

DisconnectallinputsandoutputstotheSIM983whileperformingtheautocalibration.Tocalibrate,issuethecommandACAL,orpressthebutton[polarity]andoneof[gain]atthesametime.Thecalibration completesandtheinstrumentisreadyforoperationwithin2seconds.Ifautocalibrationisunsuccessful,forexamplebecausean externalvoltage(whichcannotbenulled)isappliedtotheinput,the calibrationparametersreverttotheiroriginalvaluesandthecommandLDDE? willreturnCode1.

Autocalibrationdoesnotaffectgainaccuracy.

2.3 AC Characteristics

2.3.1 Bandwidth

Thegain-bandwidthproduct(GBP)oftheSIM983isameasureof its small-signal behavior, and depends on |G| . Four gain ranges correspondtofourvaluesofgain-bandwidthproduct, aspecified in the table on Page vi. For |G| ≥ 1 , the -3 dB small-signal bandwidth of the amplifier is f_-3dB = GBP / |G| . For |G| < 1 , f_-3dB(G) f_-3dB(G = 1.00) .

Thegain-bandwidthproductisdeterminedbyacompensationcapacitorinthefeedbackpathofthegain-stageamplifier.Itispossible tooverridethevalueofthiscapacitor,givingtheinstrumentmore bandwidth.Todothis,usethecommandBWTH.Ifthebandwidth isalteredinthisway,thenextfront-panelbuttonpresswillreturn the bandwidth to the value appropriate for the current gain. Cyclingthepowerorperforminganautocalibrationwillalsoreturnthe bandwidthtoitsdefaultvalueforthegain.

Ifthebandwidthissettoavalueotherthanitsdefault,theamplifiermayexhibitslowsettling,excessiveringing,oroscillations.

Thesmall-signalsettlingtimeoftheamplifierisacomplexfunction ofitsgainanditsbandwidth.

2.3.2 Slew rate

The slew rate of an amplifier is a measure of its large-signal behavior. It is the maximum rate of change of the output voltage, measured in V/s. The slew rate (SR) determines the maximum undistorted AC signal that can be output; forasine-wave output at a frequency f, the maximum peak-peak voltage is |V_-V_| = SR/( f) . The SIM983 is designed to be able to output a full-rangesinewave at 1 MHz.

If the outputor an intermediate stage of the amplifier is driven beyond the limits in the table on Pagevi, large-signal behavior is not guaranteed.

2.4 Clock Stopping

ThemicroprocessorclockoftheSIM983stopsifthemoduleisidle, "freezing"thedigitalcircuitry.Thefollowingactions"wakeup"the clock:

1. Apower-on.
2. Apressofafront-panelbutton.
   3.Activity(sendorreceive)attheremoteinterface.
3. Anoverload.

Theclockrunsforaslongasisnecessarytocompleteagainoroffset adjustment,ortocommunicatetheoutputofaquerythroughthe remoteinterface.However,theclockwillremainactiveforaslong astheoverloadconditionexists.

This default behavior can be modified with the remote command AWAK. Setting AWAK ON will prevent the clock from stopping. The module returns to AWAK OFF upon power-on.

3 Remote Operation

ThischapterdescribesoperatingtheSIM983overtheserialinterface.

In This Chapter

3.1IndexofCommonCommands......3-2
3.2AlphabeticListofCommands......3-4
3.3Introduction....3-6

3.3.1 Power-onconfiguration......3-6
3.3.2Buffers....3-6
3.3.3DeviceClear....3-6

3.4Commands....3-7

3.4.1 Commandsyntax....3-7
3.4.2 Notation....3-8
3.4.3Examples....3-8
3.4.4 General commands....3-9
3.4.5Configurationcommands......3-10
3.4.6 Calibration commands....3-11
3.4.7Statuscommands....3-11
3.4.8Interfacecommands....3-14
3.4.9 Serialcommunicationcommands.....3-17

3.5 Status Model 3-19

3.5.1StatusByte(SB)....3-20
3.5.2ServiceRequestEnable(SRE)......3-20
3.5.3 StandardEventStatus(ESR)......3-20
3.5.4 StandardEventStatusEnable(ESE).....3-21
3.5.5CommunicationErrorStatus(CESR).....3-21
3.5.6CommunicationErrorStatusEnable(CESE)3-22
3.5.7OverloadStatus(OLSR)......3-22
3.5.8OverloadStatusEnable(OLSE)......3-23

3.1 Index of Common Commands

SymbolDefinition

fFloating-pointvalue

iBitnumber(0–7)

jUnsignedinteger(0-255)

mUnsignedinteger(0-3)

zLiteraltoken

(?) Requiredforqueries;illegalforsetcommands

varParameteralwaysrequired

{var} Requiredparameterforsetcommands;illegalforqueries

[var]Optionalparameterforbothsetandqueryforms

General

HELP(?) 3–9InstrumentHelp

AWAK(?) {z} 3 - 10 Keep Clock Awake

Configuration

GAIN(?) {f} 3-10 Gain

OFST(?) {f} 3-10 Offset

BWTH(?) [m] 3-11 Bandwidth

Calibration

ACAL 3–11 Autocalibration

Status

*CLS 3-11 ClearStatus

*STB? [i] 3-12 Status Byte

*SRE(?) [i,] {j} 3 - 12 Service Request Enable

*ESR? [i] 3 – 12 Standard Event Status

*ESE(?) [i,] {j} 3-12 Standard Event Status Enable

CESR? [i] 3-12 Communication Error Status

CESE(?) [i,] {j} 3-13 Communication Error Status Enable

OLSR? [i] 3-13 Overload Status

OLSE(?) [i,] {j} 3-13 Overload Status Enable

PSTA(?) {z} 3-13 Pulse STATUS Mode

LBTN? 3-13 LastButton

OVLD? 3-14 Overload

Interface

*RST 3-14 Reset

*IDN? 3–15 Identify

*TST? 3 – 15 Self Test

*OPC(?) 3-15OperationComplete

CONS(?) {z} 3-15 Console Mode

LEXE? 3-16ExecutionError

LCME? 3-16CommandError

LDDE? 3-17DeviceError

TOKN(?) {z} 3-17 Token Mode

TERM(?) {z} 3-17 Response Termination

Serial Communications

PARI(?) {z} 3-18 Parity

3.2 Alphabetic List of Commands

★

*CLS 3-11ClearStatus
*ESE(?) [i,] {j} 3-12 Standard Event Status Enable
*ESR? [i] 3–12StandardEventStatus
*IDN? 3–15Identify
*OPC(?) 3-15OperationComplete
*RST 3-14Reset
*SRE(?) [i,] {j} 3-12 Service Request Enable
*STB? [i] 3–12StatusByte
*TST? 3–15SelfTest

A

ACAL 3–11 Autocalibration

AWAK(?) {z} 3-10 Keep Clock Awake

B

BWTH(?) [m] 3-11 Bandwidth

C

CESE(?) [i,] {j} 3-13 Communication Error Status Enable
CESR? [i] 3-12 Communication Error Status
CONS(?) {z} 3-15 Console Mode

G

GAIN(?) {f} 3-10 Gain

H

HELP(?) 3–9 InstrumentHelp

L

LBTN? 3-13LastButton

LCME? 3-16CommandError

LDDE? 3-17DeviceError

LEXE? 3-16ExecutionError

0

OFST(?) {f} 3-10 Offset

OLSE(?) [i,] {j} 3-13 Overload Status Enable

OLSR? [i] 3-13 Overload Status

OVLD? 3-14Overload

P

PARI(?) {z}	3-18 Parity
PSTA(?) {z}	3-13 Pulse ¬STATUS Mode

T

TERM(?) {z}	3-17 Response Termination
TOKN(?) {z}	3-17 Token Mode

3.3 Introduction

RemoteoperationoftheSIM983istroughasimplecommandlanguagedocumentedinthischapter.Bothsetandqueryformsofmost commandsaresupported,allowingtheusercompletecontrolofthe amplifierfromaremotecomputer,eitherthroughtheSIM900MainframeordirectlyviaRS-232(seeSection1.6.2.1).

SeeTable1.1forthespecificationoftheDB-15SIMInterfaceConnector.

3.3.1 Power-on configuration

The initial settings for theremote interface are 9600 baud with no parity and no flow control, and with locale chodisabled (CONS OFF).

The values of the gain and the offsetarer retained in non-volatile memory. Upon power-on, those settingsarer restored to their values before the power wasturned off. The bandwidth this set to the value appropriate for the stored gain.

Whereappropriate, thedefaultorpower-onvalueforparametersis listedinboldfaceinthecommanddescriptions.

3.3.2 Buffers

TheSIM983storesincomingbytesfromthehostinterfaceina64-byteinputbuffer.Charactersaccumulateintheinputbufferuntil a command terminator (either CR or LF ) is received, at which pointthemessageis parsed and executed.Queryresponsesfrom theSIM983arebufferedina64-byteoutputqueue.

If the input buffer overflows, then all data in both the input buffer and the output queue are discarded, and an error is recorded in the CESRandESRstatus registers.

3.3.3 Device Clear

TheSIM983hostinterfacecanbeasynchronouslyresettoitspower-onconfigurationbysendinganRS-232-stylesignal.Fromthe SIM900Mainframe,thisisaccomplishedwiththeSRST command; ifdirectlyinterfacingviaRS-232,thenuseaserialbreaksignal.After receiving the Device Clear, the CONS mode is turned OFF. Note that thisonlyresetsthecommunicationinterface;thebasicfunctionof theSIM983isleftunchanged;toresettheamplifier,use*RST.

TheDeviceClearsignalwillalsoterminatetheoutputoftheHELP?commandfromtheSIM983.

3.4 Commands

Thissectionprovidessyntaxandoperationaldescriptionsforremote commands.

3.4.1 Command syntax

The four letter mnemonic (shown in CAPS) in each command sequence specifies the command. Therest of these sequence consists of parameters.

Commandsmaytakeeithersetorqueryform,dependingonwhether the“?”characterfollowsthemnemonic.Setonlycommandsare listed without the “?”, query only commands show the “?” after the mnemonic,andoptionallyquerycommandsaremarkedwitha“(?)”.

Parametersshownin{ } and[]arenotalwaysrequired.Parameters in{ } arerequiredtosetavalue,andshouldbeomittedforqueries.Parametersin[]areoptionalinbothsetandquerycommands.Parameterslistedwithoutsurroundingcharactersarealwaysrequired.

Donotsend()or{ } or[]aspartofthecommand.

Multipleparametersareseparatedbycommas.Multiplecommands maybesentononecommandlinebyseparatingthemwithsemicolons(;)solongastheinputbufferdoesnotoverflow.Commands are terminated by either CR or LF characters. Null commands andwhitespacesareignored.Executionofthecommanddoesnot beginuntilthecommandterminatorisreceived.

tokens Token parameters (generically shown as z in the command descriptions) can be specified either as a key word or an integer value. Command descriptions list the valid keyword options, with each keyword followed by its corresponding integer value. Forexample, to set the response termination sequence to CR + LF , the following two commands are equivalent:

TERM CRLF —or— TERM 3

Forqueriesthatreturntokenvalues,thereturnformat(keywordor integer)isspecifiedwiththeTOKN command.

3.4.2 Notation

The following tables summarize the notation used in the command descriptions:

SymbolDefinition

fFloating-pointvalue

iBitnumber(0–7)

jUnsignedinteger(0–255)

mUnsignedinteger(0-3)

zLiteraltoken

(?) Requiredforqueries;illegalforsetcommands

varParameteralwaysrequired

{var} Requiredparameterforsetcommands;illegalforqueries

[var]Optionalparameterforbothsetandqueryforms

3.4.3 Examples

Each command is provided with a simple example illustrating its usage. In these examples, all data sent by the host computer to the SIM983 are set as straight teletype font, while responses received by the host computer from the SIM983 are set as slanted teletype font.

The usage examples vary with respect to query, optional parameters, and token formats. These examples are not exhaustive, and are intended to provide a convenient starting point for user programming.

3.4.4 General commands

InstrumentHelpHELP(?)

OutputsacondensedversionofSection3.4totheremoteinterface.

HELP maybeusedwithorwithoutthequerysign,withthesame effects.

HELP?Example:

Notation:

fisafloating-pointnumber;

iisbitnumber(0..7);

jisan8-bitunsignedinteger(0..255);

misa2-bitunsignedinteger(0..3);

zisatoken

(?)questionrequiredforqueries,illegalforsetcommands;

[]=parameterisoptionalforbothsetandqueryforms;

{}=parameterisrequiredtoset,illegalforqueries;

parameterwithoutbracketsisalwaysrequired;

thebracketsthemselvesshouldnotbesent.

General commands:

HELP?-Sendthistext.

AWAK(?) {z}-Keepthemoduleclockawake.

Configurationcommands:

GAIN(?) {f}-Set/querygain.

OFST(?) {f}-Set/queryoffset.

BWTH(?) [m]-Outputbandwidth.

Calibrationcommands:

ACAL-One-timeautocalibration.

Statuscommands:

*CLS-ClearStatus.

*STB?[i]-QuerytheStatusByte.

*SRE(?) [i, ] {j} -ServiceRequestEnable.

*ESR?[i]-QueryStandardEventStatusregister.

*ESE(?) [i, ] {j} - StandardEventStatusEnable.

CESR?[i]-QuerytheCommunicationsErrorStatus.

CESE(?) [i, ] {j} - CommunicationsErrorStatusEnable.

OLSR?[i]-QueryOverloadStatusregister.

OLSE(?) [i, ] {j} -OverloadStatusEnable.

PSTA(?){z}-PulseStatusorchangeitslevel.

LBTN?-Whichbuttonlastpressed?

OVLD?-Inputoroutputcurrentlyoverloaded?

	Interfacecommands:*RST-Resettoknownstate.*IDN?-Identify.*TST?-Doesnothing.*OPC(?)-Operationcomplete.CONS(?){z}-ConsoleOFF/ON.LEXE?-LastExecutionError.LCME?-LastCommunicationsError.LDDE?-LastDevice-DependentError.TOKN(?){z}-TurntokenmodeOFF/ON.TERM(?){z}-Cmdlineend(NONE,CR,LF,CRLF,LFCR).Serialinterfacecommand(baudrateisalways9600):PARI(?){z}-Parity(NONE,EVEN,ODD,MARK,SPACE).
AWAK(?) {z}	Keep Clock AwakeSet (query) the SIM983 keep-awake mode {to z = (OFF 0, ON 1)}.Ordinarily, the clock oscillator for the SIM983 microcontroller is held in a stopped state, and only enabled during processing of events (Section 2.4). Setting AWAK ON forces the clock to stay running, and isusefulonlyfordiagnosticpurposes.
Example:	AWAKON

3.4.5 Configuration commands

GAIN(?) {f}	Gain
	Set (query) the amplifier gain {to f}. The module accepts signed floating-point values in the ranges -19.99 ≤ f ≤ -0.01, 0.01 ≤ f ≤ 19.99 . The reset value is f = +1.00 .
	AfteraGAIN setcommand,thebandwidthissettothevalueappropriateforthenewgain.Gainqueriesdonotalterthebandwidth.
Example:	GAIN1.4232E1;GAIN?+14.23
OFST(?) {f}	Offset
	Set (query) the offset of the amplifier {to f volts}. The module accepts signed floating-point values in the range -10.000 ≤ f ≤ 10.000 . The reset value is f = 0.000 .
	Settingorqueryingtheoffsetdoesnotchangethebandwidth.

OFST-7.032;OFST?Example: -07.030

BandwidthBWTH(?) [m]

Set(query)thegain-bandwidthproductoftheamplifier[tom].Allowedvaluesoftheoptionalparameterare0through3,withalarger valuecorrespondingtoagreatergain-bandwidth. Whenthegainis setfromthefrontpanelorfromtheremoteinterface,thebandwidth automaticallyrevertstothefollowing:

RangeBandwidthmGBP,MHzmin

0.01 ≤ |G| ≤ 2.39	0	3.0 (|G| ≥ 1.00)
2.40 ≤ |G| ≤ 4.19	1	5.0
4.20 ≤ |G| ≤ 9.59	2	10.0
9.60 ≤ |G| ≤ 19.99	3	17.0

The bandwidth is also automatically selected from this table if the optionalparameterisomitted.
Example: GAIN17; BWTH1; BWTH? 1 GAIN17; BWTH? 3

3.4.6 Calibration commands

ACAL	AutocalibrationPerform a self-calibration (Section 2.2). Make sure to disconnect all inputsandoutputstotheSIM983,andtosettheoutputtozero.Remote commands are not processed until ACAL is complete.
	Example: ACALLDDE?0checksforsuccessofanautocalibration.

3.4.7 Status commands

TheStatuscommandsqueryandconfigureregistersassociatedwith statusreportingoftheSIM983. SeeSection3.5forthestatusmodel.

*CLS ClearStatus *CLS immediatelyclearstheESR,CESR,andOLSRstatusregisters. Example: *CLS

	StatusByte*STB? [i]QuerytheStatusByteregister[Biti].Executionofthe*STB? query(withouttheoptionalBiti)always causes the ¬STATUS signal to be deasserted. Note that *STB? i will not clear ¬STATUS, even if Bit i is the only bit presently causing the ¬STATUSsignal.*STB?Example:16
*SRE(?) [i,] {j}	Service Request EnableSet (query) the Service Request Enable register [Bit i] {to j}.*SRE0, 1Example:
	StandardEventStatus*ESR? [i]QuerytheStandardEventStatusRegister[Biti].Uponexecutionof*ESR?,thereturnedbit(s)oftheESRregisterare cleared.*ESR?Example:64
*ESE(?) [i,] {j}	Standard Event Status EnableSet (query) the Standard Event Status Enable register [Bit i] {to j}.*ESE6, 1Example:ESE?64
CESR? [i]	Communication Error StatusQuerytheCommunicationErrorStatusRegister[Biti].UponexecutingaCESR? query,thereturnedbit(s)oftheCESRregisterarecleared.CESR?Example:0
CESE(?) [i,] {j}	Communication Error Status EnableSet(query)theCommunicationErrorStatusEnableregister[Biti]{toj}.CESE?Example:2
	OverloadStatusOLSR? [i]QuerytheOverloadStatusRegister[Biti].UponexecutinganOLSR? query,thereturnedbit(s)oftheOLSRegisterarecleared.0LSR?Example:3
OLSE(?) [i,] {j}	Overload Status EnableSet (query) the Overload Status Enable register [Bit i] {to j}.0LSE4Example:
PSTA(?) {z}	Pulse ¬STATUS ModeSet (query) the Pulse ¬STATUS mode {to z = (OFF 0, ON 1)}.When PSTA ON is set, all new service requests will only pulse the ¬STATUS signal LOW (for a minimum of 1 μs). The default behavior istolatch¬STATUSLOWuntila*STB? queryisreceived.A reset does not alter PSTA. The value in boldface above is the power-on value.PSTA?Example:OFF
LBTN?	LastButtonQuerythenumberofthelastbuttonpressed. Theresponse is LBTN? Lastbutton1 [polarity]2 [gain]3 [gain]4 [offset]5 [offset]6 Both[gain]and[gain](reset gain)7 Both [offset] and [offset] (reset offset)8 One of [gain] and [polarity] (autocalibrate)

Thevalue@isreturnedifnobuttonwaspressedsincethelastLBTN?.

AqueryofLBTN? alwaysclearsthebuttoncode,soasubsequentLBTN? willreturn0.

LBTN?Example: 5

OverloadOVLD?

Querythecurrentoverloadcondition.Theresponseis

OVLD? Overloaded

1Input

2Input+offset

4Output

Combinationoverloadsarereportedbysummingthevaluesoftheindividualoverloadflags.ThiscommandcomplementstheOLSRstatusregisterdescribedinSection3.5.7,andthethreeoverloadflags correspondone-to-onewithbitsinOLSR.However,oncecleared byOLSR? or*CLS,theoverloadstatusbitswillstayclearedeven though the overload condition may persist and remain reported byOVLD?.

OVLD?Example:

6

implies that the input is not overloaded; the intermediate stage (V_in + V_ofs) isoverloaded; and the output is overloaded.

3.4.8 Interface commands

TheInterfacecommandsprovidecontrolovertheinterfacebetween theSIM983andthehostcomputer.

*RST

Reset

ResettheSIM983toitsdefaultconfiguration.

*RST setsthefollowing:

• Clock oscillator to stop during idle time (AWAK 0FF).
• Gain to +1.00.
• Offset to 0.000 V.
• Bandwidthto0.
• ThetokenmodetoOFF.

*RST does not affect PSTA, CONS, TERM, and all service-enable registers (*SRE, *ESE, CESE, or OLSE).

3.4Commands3-15

	*RSTExample:CONS?1
	Identify*IDN?Querythedeviceidentificationstring.Theidentificationstringisformattedas:StanfordResearchSystems, SIM983, s/n******, ver#. ####whereSIM983isthemodelnumber,*****isa6-digitserialnumber,and#.###isthefirmwarerevisionlevel.*IDN?Example:StanfordResearchSystems, SIM983, s/n004900, ver2.0
	SelfTest*TST?Thereisnointernalself-testintheSIM983afterthepower-on,sothis queryalwaysreturns0.*TST?Example:0
	OperationComplete*OPC(?)SetstheOPCflagintheESRregister.The query form *OPC? writes a 1 into the output queue when complete,butdoesnotaffecttheESRregister.*OPC?Example:1
CONS(?) {z}	Console ModeSet (query) the console mode {to z = (OFF 0, ON 1)}.CONS causeseachcharacterreceivedattheinputbuffertobecopied totheoutputqueue.A reset does not alter CONS. The value in boldface above is the power-on value. CONS is set to 0FF upon Device Clear.Example: CONS ON

ExecutionErrorLEXE?

QuerytheLastExecutionErrorcode.AqueryofLEXE? always clearstheerrorcode,soasubsequentLEXE? willreturn0. Valid codesare:

ValueDefinition

0NoexecutionerrorsincelastLEXE?

1Illegalvalue

2Wrongtoken

3Invalidbit

*STB?12;LEXE?;LEXE?Example:

3

0

Theerror(3,"Invalidbit")isbecause*STB? onlyallowsbit-specific queriesof0-7.ThesecondreadofLEXE? returns0.

CommandErrorLCME?

QuerytheLastCommandErrorcode.AqueryofLCME? always clearstheerrorcode,soasubsequentLCME? willreturn0. Valid codesare:

Value | Definition

0NocommanderrorsincelastLCME?

1Illegalcommand

2Undefinedcommand

3Illegalquery

4Illegalset

5Missingparameter(s)

6Extraparameter(s)

7Nullparameter(s)

8Parameterbufferoverflow

9Badfloatingpoint

10Badinteger

11Badintegertoken

12Badtokenvalue

14Unknowntoken

Example: *IDN

LCME?

4

Theerror(4,"Illegalset")isduetothemissing"?"

	DeviceErrorLDDE?QuerytheLastDevice-DependentErrorCode.AqueryofLDDE?alwaysclearstheerrorcode,soasubsequentLDDE? willreturn0. Validcodesare:ValueDefinition
	0NoexecutionerrorsincelastLEXE?1Unabletoautocalibrate
	ACALExample:LDDE?0indicatesasuccessfulautocalibration.
	TokenModeTOKN(?) {z}Set (query) the token query mode {to z = (OFF 0, ON 1)}.If TOKN ON is set, then queries to the SIM983 that return tokens will return a text keyword; otherwise they return a decimal integer value. Thus, the only possible responses to the TOKN? query are ON and 0.
Example:	TOKNOFF
TERM(?) {z}	Response TerminationSet (query) the <term> sequence {to z = (NONE 0, CR 1, LF 2, CRLF 3, orLFCR4)}.The <term> sequence is appended to all query responses sent by the module, and is constructed of ASCII character(s) 13 (carriage return)and10(linefeed).Thetokenmnemonicgivesthesequence ofcharacters.A reset does not alter TERM. The value in boldface above is the power-onvalue.
Example:	TOKNON; TERM?CRLF

3.4.9 Serial communication commands

NotethattheSIM983canonlysupportasinglebaudrateof9600, and does not support flow control. A reset does not change the serial interfacesettings;useDeviceClear.

ParityPARI(?) {z}

Set (query) the parity {to z = (NONE 0, ODD 1, EVEN 2, MARK 3, SPACE4)}. The value in bold face is the power-on-value.

TOKNON; PARI? Example: EVEN

3.5 Status Model

TheSIM983statusregistersfollowthehierarchicalIEEE-488.2for-statusregisters mat.AblockdiagramofthestatusregisterarrayisgiveninFigure3.1.

graph TD
    A["Communication Error Status"] --> B["DCAS: Device Clear 7"]
    A --> C["CTSH: CTS Halted 6"]
    A --> D["RTSH: RTS Halted 5"]
    A --> E["OVR: Input Buffer Overrun 4"]
    A --> F["HWOVRN: Hardware Input Overrun 3"]
    A --> G["NOISE: Noise Error 2"]
    A --> H["FRAME: Framing Error 1"]
    A --> I["PARITY: Parity Error 0"]
    A --> J["CESR CESE"]
    K["Standard Event Status"] --> L["PON: Power On 7"]
    K --> M["URQ: User Request 6"]
    K --> N["CME: Command Error 5"]
    K --> O["EXE: Execution Error 4"]
    K --> P["DDE: Device Error 3"]
    K --> Q["QYE: Query Error 2"]
    K --> R["INP: Input Buffer Error 1"]
    K --> S["OPC: Operation Complete 0"]
    K --> T["ESR ESE"]
    U["Overload Status"] --> V["undef X"]
    U --> W["undef X"]
    U --> X["undef X"]
    U --> Y["undef X"]
    U --> Z["undef X"]
    U --> AA["Output 2"]
    U --> AB["Input + Offset 1"]
    U --> AC["Input 0"]
    U --> AD["OLSR OLSE"]
    AE["Status Byte"] --> AF["7"]
    AE --> AG["X"]
    AE --> AH["X"]
    AE --> AI["X"]
    AE --> AJ["X"]
    AE --> AK["X"]
    AE --> AL["X"]
    AE --> AM["X"]
    AE --> AN["X"]
    AE --> AO["X"]
    AE --> AP["X"]
    AE --> AQ["X"]
    AE --> AR["X"]
    AE --> AS["X"]
    AE --> AT["X"]
    AE --> AU["X"]
    AE --> AV["X"]
    AE --> AW["X"]
    AE --> AX["X"]
    AE --> AY["X"]
    AE --> AZ["X"]
    AE --> BA["X"]
    AE --> BB["X"]
    AE --> BC["X"]
    AE --> BD["X"]
    AE --> BE["X"]
    AE --> BF["X"]
    AE --> BG["X"]
    AE --> BH["X"]
    AE --> BI["X"]
    AE --> BJ["X"]
    AE --> BK["X"]
    AE --> BL["X"]
    AE --> BM["X"]
    AE --> BN["X"]
    AE --> BO["X"]
    AE --> BP["X"]
    AE --> BQ["X"]
    AE --> BR["X"]
    AE --> BS["X"]
    AE --> BT["X"]
    AE --> BU["X"]
    AE --> BV["X"]
    AE --> BW["X"]
    AE --> BX["X"]
    AE --> BY["X"]
    AE --> BZ["X"]

Figure3.1: StatusregistermodelfortheSIM983ScalingAmplifier.

TherearetwocategoriesofregistersintheSIM983statusmodel:

EventRegisters: Theseread-only registers record the occurrence of defined events. If the event occurs, the corresponding bit is set to 1. Upon querying an event register, allset bits within it are cleared. These are sometimes known as "sticky bits," since once set, a bit can only be cleared by reading its value. Event registernamesend with SR.

Enable Registers: These read/write registers define a bitwise mask for their corresponding event register. If a bit position is set in an event register while the same bit position is also set in the enable register, then the corresponding summary bit message is set. EnableregisternamesendwithSE.

Atpower-on, all status registers are cleared.

IDLE:Indicates that the input buffer is empty and the command parser is idle. Can be used to help synchronize SIM983 query responses.

ESB:EventStatusBit.Indicateswhetheroneormoreoftheenabled eventsintheStandardEventStatusRegisteristrue.

MSS:MasterSummaryStatus.Indicateswhetheroneormoreofthe enabledstatusmessagesintheStatusByteregisteristrue.

CESB:CommunicationErrorSummaryBit.IndicateswhetheroneormoreoftheenabledflagsintheCommunicationErrorStatusRegisterhasbecometrue.

3.5.2 Service Request Enable (SRE)

EachbitintheSREcorrespondsone-to-onewithabitintheSBregister,andactsasabitwiseANDoftheSBflagstogenerateMSS.Bit6of theSREisundefined—settingithasnoeffect,andreadingitalways returns0.Thisregisterissetandqueriedwiththe*SRE(?) command.

Atpower-on, thisregisteriscleared.

3.5.3 Standard Event Status (ESR)

TheStandardEventStatusRegisterconsistsof8eventflags. These event flags are all "sticky bits" that are set by the corresponding events, and cleared only by reading or with the *CLS command. Reading a single bit (with the *ESR? i query) clears only Bit i.

WeightBitFlag

10	OPC
21	INP
42	QYE
83	DDE
164	EXE
325	CME
646	URQ
1287	PON

OPC:OperationComplete.Setbythe*OPC command.

INP:Inputbuffererror.Indicatesdatahasbeendiscardedfromthe inputbuffer.

QYE:QueryError.Indicatesdataintheoutputqueuehasbeenlost.

DDE:Device-DependentError.Indicates a failed autocalibration.

EXE:ExecutionError.Indicate the error in a command that was successfully parsed. Out-of-range parameters are an example.

CME:CommandError.Indicatesacommandparser-detectederror.

URQ:UserRequest.Indicatestatafront-panelbuttonwaspressed.

PON:PowerOn.Indicatesthatanoff-to-ontransitionhasoccurred.

3.5.4 Standard Event Status Enable (ESE)

TheESEactsasabitwiseANDwiththeESRregistertoproducethe single-bitESBmessageintheStatusByteRegister(SB).Theregister canbesetandqueriedwiththe*ESE(?) command.

Atpower-on, thisregisteriscleared.

3.5.5 Communication Error Status (CESR)

TheCommunicationErrorStatusRegisterconsistsof8eventflags; eachoftheflagsissetbythecorrespondingevent,andclearedonly byreadingtheregisterorwiththe*CLS command.Readingasing single bit (with the CESR? i query) clears only Bit i.

WeightBitFlag

10PARITY

21FRAME

42NOISE

83HWOVRN

164OVR

325RTSH

646CTSH

1287DCAS

PARITY:Parityerror.Setbyserialparitymismatchontheincomingdata byte.

FRAME:Framingerror.Setwhenanincomingserialdatabyteismissing theSTOPbit.

NOISE:Noiseerror.Setwhenanincomingserialdatabytedoesnot presentasteadylogiclevelduringeachasynchronousbit-periodwindow.

HWOVRN:HardwareOverrun.Setwhenanincomingserialdatabyteis lostduetointernalprocessorlatency.Causestheinputbuffer tobeflushed,andresetsthecommandparser.

OVR:InputbufferOverrun.Setwhentheinputbufferisoverrunby theincomingdata.Causestheinputbuffertobeflushed,and resetsthecommandparser.

RTSH:RTSHoldoffEvent.UnusedintheSIM983.

CTSH:CTSHoldoffEvent.UnusedintheSIM983.

DCAS:DeviceClear. Indicate that the SIM983 received the Device Clear signal (an RS-232 ). Clears the input buffer and the output queue, and reset the command parser.

3.5.6 Communication Error Status Enable (CESE)

TheCESEactsasabitwiseANDwiththeCESRregistertoproduce the single-bit CESB message in the Status Byte Register (SB). The registercanbesetandqueriedwiththeCESE(?) command.

Atpower-on, thisregisteriscleared.

3.5.7 Overload Status (OLSR)

TheOverloadStatusRegisterconsistsof3eventflags; eachofthe flags is set by the corresponding overload, and cleared only by readingtheregisterorwiththe*CLS command. Readingasinglebit (with the OLSR? i query) clears only Bit i.

Weight	Bit	Flag
1	0	Input
2	1	Input + Offset
4	2	Output
8	3	undef (0)
16	4	undef (0)
32	5	undef (0)
64	6	undef (0)
128	7	undef (0)

Input: Inputoverload.Indicate that |V in| >10.0V(see also Section 1.2.4.1).

Input + Offset : Intermediate stage overload. Indicates that |V_in + V_ofs| > 10.0V .

Output: Outputoverload. Indicate that |V_out| >10.0V .

Reading this register (with the OLSR? query) clears all overload bits that a reset. If the overload condition persists, the bit will remain cleared until the overload condition ceases and re occurs. Use OVLD? to query the current state of the overload.

3.5.8 Overload Status Enable (OLSE)

TheOLSEactsasabitwiseANDwiththeOLSRegistertoproduce thesingle-bitOLSBmessageintheStatusByteRegister(SB).The registercanbesetandqueriedwiththeOLSE(?) command.

Atpower-on, thisregisteriscleared.

4 Performance Verification

This chapter describes the tests necessary to verify the SIM983 is operating correctly and with unspecified calibration.

In This Chapter

4.1 Verifying the DC Accuracy......4-2

4.1.1 Gettingready......4-2
4.1.2 Interpreting the accuracy specifications...4-2
4.1.3 Inputbiascurrent......4-4

4.2 VerifyingACPerformance......4-4

4.2.1 Transfercharacteristic......4-4
4.2.2Stepresponse....4-4
4.2.3Slewrate....4-6
4.2.4Totalharmonicdistortion......4-6

4.3NoiseCharacteristics......4-6

4.4PerformanceTestRecord .....4-8

4.4.1DCtest ....4-8
4.4.2Noisetest .....4-9

4.1 Verifying the DC Accuracy

ThegainandtheoffsetoftheSIM983ScalingAmplifierarecalibrated atthefactory.Besidesself-calibration,therearenouser-adjustable calibrationsettings.

4.1.1 Getting ready

ToverifytheDCperformanceoftheSIM983,oneneedsaDCsignal source(abletooutputeitherpolarity)and,asaminimum,avolt-meteraccurateto±500μVorbetter.Twovoltmeterswithmatched calibrationaremostconvenient,suchastwochannelsoftheStanford ResearchSystems'SIM970QuadDVM.TheSIM928IsolatedVoltage Sourceisrecommendedasthecalibrator;however,thewiperofa potentiometer connected to a power supply can be a simpler if less convenientsolution.TheDCsourcemustbequiet.Iftheverification isdonewithonlyonevoltmeter,cableshavetobeconnectedand disconnectedbetweenmeasurements,sothevoltagesourcemustbe stablewithinthevoltmeter'saccuracy.Nosuchstabilityisrequired iftwovoltmetersareused.

1. WarmuptheSIM983foratleast2hours.
2. If the voltmeter requires a warmup of a certain duration prior to establishing its accuracy specifications, or an autocalibration, becertaint o completethese.
3. PerformanautocalibrationoftheSIM983asspecifiedinSection2.2.

Inordertoperformthemeasurements, connect the output of the voltagesourcetotheinput of the amplifier and to Voltmeter1. Connect the output of the SIM983 to Voltmeter2. If using only one voltage meter, use it to alternately measure the DC source voltage and the output voltage of the SIM983.

4.1.2 Interpreting the accuracy specifications

Gain and offset errors specified in the table on Page value contribute to the overall output error. The error in V_out = G × (V_in + V_ofs) is

$$ \delta V _ {\text { out }} = \delta G \times (V _ {\text { in }} + V _ {\text { ofs }}) + G \times \delta V _ {\text { ofs }}. $$

The gain error G and the offset error V_ofs both havetemperature-dependent contributions, mentioned in the specification table under “Stability”.

4.1.2.1 Error budget

Consider, for example, a measurement with G = +13.30 , V_in = 6.192V , and V_ofs = -5.480V , performed at a laboratory temperature of +28^ . The following are the worst-case contributions of the factor specified in the table on Pagevitothe output error:

SpecificationContributionToOverallError,V

Gain accuracy, ±0.01Gainstability,(28°C- 23C)× (±10ppm/°C)=±50× 10-6Offset accuracy, ±1 mV ± 200 ppmOffsetstability,(28°C- 23C)× (±20μV/°C± 20ppm/°C)= ±100 μV ± 100 × 10-6	±0.01 × (6.192 - 5.480) = ±0.0071±50× 106 × (6.192 - 5.480) = ±0.000013.30 × (±0.001 ± 200 × 10-6 × (-5.480)) = ±0.027913.30 × (±0.0001 ± 100 × 10-6 × (-5.480)) = ±0.0086
Total	=±0.0436

The output of the instrument is therefore

$$ V _ {\mathrm{out}} = 1 3. 3 0 \times (6. 1 9 2 \mathrm{V} - 5. 4 8 0 \mathrm{V}) \pm 0. 0 4 3 6 \mathrm{V} = (9. 4 7 \pm 0. 0 4) \mathrm{V} $$

iftheamplifierisperformingwithinitsspecifications.

Consider another example, with G = -0.19 , V_in = -3.954 V, and V_ofs = -5.480 V, performed at a laboratory temperature of +23 °C. For |G| < 1 , the specified offset error term is referenced to the output, according to Note4 on Page vii. The worst-case error budget is

SpecificationContributiontoOverallError,V

Gain accuracy,	±0.01	±0.01 × (-3.954 - 5.480) = ±0.0943
Offset accuracy,	±1 mV ± 200 ppm	±0.001 ± 200 × 10-6× (-0.19) × (-3.954 - 5.480) = ±0.0014
Total		=±0.0957

Thestabilitytermsarezerobecausethetestistakenatthecalibration temperature. TheoutputoftheSIM983istherefore

$$ V _ {\text { out }} = - 0. 1 9 \times (- 3. 9 5 4 \mathrm{V} - 5. 4 8 0 \mathrm{V}) \pm 0. 0 9 5 7 \mathrm{V} = (1. 7 9 \pm 0. 1 0) \mathrm{V} $$

iftheunitisworkingaccordingtothespecifications.

When interpreting the result of a DC performance test of the SIM983, always account for the voltmeter accuracy specifications.

4.1.2.2 Recalibration

If the module fails its DC accuracy specifications, return it to Stanford ResearchSystemsforanewcalibration.

4.1.3 Input bias current

Asimpletestoftheinputcurrentcanbedonebyconnectingthe inputoftheSIM983totheinputofavoltmeterthathasamicrovolt range,suchastheSIM970.Thecurrentwillflowthroughaparallel combinationofthe1MΩinputresistanceoftheSIM983andtheinput resistanceofthevoltmeter,whichistypically10MΩintheSIM970 andisthatorgreaterinothervoltmeters.Dividethevoltmeter readingbytheresistance(e.g.0.9MΩ)toobtainthecurrent.Acurrent thatexceedsthespecificationinthetableonPageviindicatesa damagedfrontend.ThemoduleshouldthenbereturnedtoStanford ResearchSystemsforrepair.

4.2 Verifying AC Performance

MostinformationabouttheACbehavioroftheSIM983ScalingAmplifiercanbededucedbyobservingtheresponseoftheinstrument toasquarewaveattheinput.Theequipmentrequiredforthetestis afunctiongeneratorwithatmost25nssquare-waverisetime,such astheStanfordResearchSystems'DS345,andanoscilloscopewith atleast100MHzbandwidth. AnFFTspectrumanalyzer,suchas theStanfordResearchSystems'SR785,isneededtomeasuretotal harmonicdistortionandnoise.

4.2.1 Transfer characteristic

Itispossibletomeasurethesmall-signalbandwidthoftheamplifier byapplyinga100mVpeak-peaksinewavetoitsinput,andincreasingthefrequencyoftheappliedsignaluntiltheoutputamplitude reducesto-3dB,i.e. 1 / 2 ,ofitslow-frequencyvalue.However,the small-signalbandwidthcanalsobemeasuredfromtherisetime oftheinstrument'sresponsetoasmall-inputstep.Forexample, inFigure4.1measuretherisetimeoftheoutputfrom 10% to 90% , i.e.-400mVto+400mV:

$$ t _ {\mathrm{rise}} = 1 1 1 \mathrm{ns}, $$

sothesmall-signalbandwidth

$$ f _ {- 3 \mathrm{dB}} (G = 1) = \frac {0 . 3 5}{t _ {\text { rise }}} = 3. 1 \mathrm{Mhz}, $$

which is consistent with the bandwidth expected from GBP=3.0MHzinthespecificationtableonPagevi.

4.2.2 Step response

Figures4.1-4.6 illustrate the typical responses of SIM983 to steps in the input voltage. Figure 4.2 is for G = 4.00 , a value near the

top end of the range for BWTH = 1. According to the discussion in Section5.1.2.5, the amplifier is relatively overcompensated, resulting in an increased settling time. Compare with Figure 4.3, with G = 10.00 at the low end of the range for BWTH = 3. The amplifier is relatively undercompensated, and the smaller phase margin results in some overshoot and ringing.

Figure4.1: ResponseoftheSIM983toa1.0V peak-peak step, G = +1.00 , V_ofs = 0.000V .

Figure4.2: ResponseoftheSIM983toa1.0V peak-peak step, G = +4.00, V_ofs =0.000V.

Figure4.3: Response of the SIM983 to a 1.0V peak-peak step, G = +10.00 , V_ofs = 0.000V .

Figure4.4: Response of the SIM983 to a 1.0V peak-peak step, G = +19.99 , V_ofs = 0.000V .

Theasymmetricalpositive-goingandnegative-goingresponses in Figures 4.5 and 4.6 are ultimate artifacts of the single-ended, as opposed to differential, topology of the input voltage buffer (Section5.1.2.1).

Figure4.5: ResponseoftheSIM983toa20V peak-peak step, G = +1.00, V_ofs =0.000V.

Figure4.6: Response of the SIM983 to a 20V peak-peak step, G = +0.10 , V_ofs = 0.000V .

4.2.3 Slew rate

Slewrateinformationiscontainedwithinthelarge-input,large-outputstepresponse(Figure4.5). ^2 Afteraninitialdelay,theoutput rises from -5.4 V to +5.2 V in 120 ns. The slew rate

$$ \mathrm{SR} = \frac {5 . 2 - (- 5 . 4)}{1 2 0 \times 1 0 ^ {9}} = 8 8 \mathrm{V} / \mu \mathrm{s}. $$

4.2.4 Total harmonic distortion

Figure4.7 showsadistortionmeasurementmadeontheSR785 FFTSpectrumAnalyzer.

4.3 Noise Characteristics

Figure4.8 shows noise plot of the SIM983 up to f = 100kHz , measured with an SR785. Not the quite weak dependence of the input-referenced noise on the gain for |G| ≥ 1 . Figure 4.9 shows the time dependence of the output voltage of the SIM983. The 0.17Hz single-pole high-pass, and 10Hz eighth-order low-pass filtering was provided by the SIM965 Analog Filter.

Figure4.7: Responsespectrum of theSIM983atG=+1.00toa1.0kHz, 1.0Vrmssinewave, showingharmonic artifactsat<1× 10 ^-5 oftheprincipal. The total THD for 10 harmonics is -96dB, as measured by an SR785. The THD does not degrade with highergain, or larger input signal, up to the overload limits of theSIM983.

Figure 4.8: Noise of the SIM983, referenced to the input for |G| ≥ 1 .

Figure 4.9: 0.1 Hz to 10 Hz noise of the SIM983, G = +19.99, additional gain of 50.

4.4 Performance Test Record

4.4.1 DC test

Serialnumber

Labtemperature(°C)=

G	V_in (V)(V)	V_ofs (V)	V_out (V)	G × _in + V_ofs (V)	Error(V)	Gain accuracy error (V)	Gain stability error (V)	Offset accuracy error (V)	Offset stability error (V)	Cal within spec?
						12

4.4.2 Noise test

Serialnumber

Inputbiascurrent(pA)=

Noisevolage, nV/ √Hz:

	G = -0.10	G = +0.10	G = -1.00	G = +1.00	G = -19.99	G = +19.99
f=1kHz
f=10kHz

5 Circuit Description

ThischapterpresentsabriefdescriptionoftheSIM983circuitdesign. Acompletepartslistandcircuitschematicsareincluded.

In This Chapter

5.1 CircuitDiscussion....5-2

5.1.1 Microcontrollerinterface......5-2

5.1.2Theamplifier....5-2

5.1.3Frontpanel....5-6

5.2PartsList....5-6

5.3SchematicDiagrams....5-10

5.1 Circuit Discussion

The following sections correspond to schematic pages at the end of the manual.

5.1.1 Microcontroller interface

TheSIM983iscontrolledbymicrocontrollerU107.

5.1.1.1 Digital control and clock stopping

Acriticalaspectofthedesignistheclock-stopcircuitryimplemented byU102andU105.AsimpleRCoscillatorisenabledordisabledat Pin1ofU105.Thispinisdrivenbysynchronizingflip-flopU102Bto ensurethatno"runt"clockpulsesareproducedthatwouldviolate theminimunclockperiodofU107.Fourseparateclockstarting signalsarecombinedbyU103andU104,asdiscussedinSection2.4.

ThefaststarttimeoftheRCoscillatorensuresthatincomingserialdatawillbecorrectly decodedbythemicrocontroller'sUART, evenwhentheclockisstartedbytheserialstartbitoftheincoming data.Whenthemicrocontrollerhascompletedallpendingactivity, itdrivestheSTOPsignalHIGH(Pin71ofU107), effectivelyhalting its own processor clock. In this way, the SIM983 guarantees that no digitalclockartifactscanbegeneratedduringquiescentoperation.

5.1.1.2 Power and grounds

Aseparateclean+5 VsourceisprovidedbyvoltageregulatorU109 topowertheanalogcircuitryoftheamplifier. Eachpointinthe circuitthatconnectstoGround2(Section2.1.2)isseparatelyrouted toPin8ofinterfaceconnectorJ101,formingastargroundonLayer3 ofthecircuitboard.

5.1.2 The amplifier

The signal path in the SIM983 Scaling Amplifier consists of five stages: the high-impedance input voltage buffer, the summing amplifier, the voltage inverter, the programmable gain stage, and the passive LRC filter. Other part of the amplifier circuit are the precision voltage reference, the offset voltage generator, and the output microvoltmeter, used for autocalibration.

5.1.2.1 Input voltage buffer

The input buffer is a high-impedance (40pA max bias current), high-slew-rate (1200 V/ s typ.), high-speed (105 MHz typ. small-signal

bandwidth)compositeoperationalamplifier,runningatgain1.Cas-codedradiofrequencyFETQ201providestheslewrateandthebandwidth,whereasU201,aprecisionJFEToperationalamplifier(op-amp),disciplinesQ201toamaximumof900μVofoffsetvoltage, 12μV/°Cmaximumoffsetdrift,and8.5nV/√Hztypicalnoise. ^1 The outputofthevoltagebufferismonitoredforoverloadbycomparatorU213,whichtripsatthevoltagelimitsspecifiedinSection1.2.4.1.

5.1.2.2 Offset voltage generator

TheoffsetvoltageisprovidedbyU204,a16-bitdigital-to-analogconverter(DAC).BecauseoftheultralowdriftoftheDACandprecision resistornetworkR215,thetemperaturestabilityofthegenerated offsetislargelydeterminedbythe5ppm/ °Ctypicalperformance of scaling resistor R217. The integral nonlinearity of U204 puts a200ppmlimitontheoverallaccuracyoftheinstrument'soffset. Asecond,12-bitDACU206allowsforfinetuningofthegenerated offset,cancellingthecontributionoftheinputoffsetvoltageofU201 andoffsetsinsubsequentstagesinordertoachievethespecifiedaccuracy. The offset voltage is filtered by the 6.3 kΩ output resistance ofU204incombinationwithC206,withf -3dB =11Hz.

5.1.2.3 Summing amplifier

The voltagesattheoutputsoftheinputbufferandthetwooffset-generating DACs are combined by a summing amplifier built aroundU208A. Thislow-noise, high-speedop-ampisdisciplined byonehalfofprecisionop-ampU207, soitsinputoffsetcontributes negligibly to the overall offset error and the offset drift. However, the inputbiascurrentoftheop-ampdoescontributetotheerror, and thiscontributionispartiallycancelledbyaconstantcurrentinjected intothesummingnodethroughR219. Theremainingcontribution iscalibratedoutviaU204andU206.

At this stage, three major contributions to the overall noise of theSIM983comeintoplay;thesecontributionsarecomparablein magnitude,andaddinquadrature.The1.5nV/ noise(at10kHz) ofU208facesanoisegainof6fromR216andR217. Theinput buffercontributesanother9.5nV/ . Finally,theJohnsonnoise ofthe2.5kΩresistorsofR216andthe604ΩR217,timesthenoise gain,yields16.5nV/ ,referencedtotheinput. Therefore,the totalnoiseattheoutputofthisstageistypically21nV/ . The inputbiascurrentofU208,passingthroughthefeedbackportion

ofR216,onlygeneratesacontributionof3nV/whenaddedinquadrature.

,insignificant

ScalingresistornetworkR216ishighlystable, and does not contribute appreciably to the drift of the regain.

5.1.2.4 Voltage inverter

Theinverson, ifrequired, is performed by the other half of dual op-ampU208. Precision resistornetwork R222 is connected in such a way that thenoise gain of the op-ampis always 2, ensuring stability from oscillation. The Johnson noise of thenetwork contributes the overall noise of the SIM983, resulting in 22nV/ (typ., at 10kHz) atthestage's output.

Because the inverting stage is not disciplined, its offset contributes to the overall error; this offset typically drifts by 10 V/^ , and, combined with the drift of the input voltage buffer, this error determines the offset stability of the instrument. The error produced by the input bias current of the op-ampiscalibrated out.

The output of the summing amplifier is monitored for overload by comparator U214, triggered at the voltage limits discussed in Section1.2.4.1.

5.1.2.5 Gain stage

The variable-gainelement is one half of high-speedop-ampU211, connected in the inverting configuration. Two matched converters of dual multiplying DAC(MDAC)U210 serve as variable input and feedback resistors for this inverting amplifier:

$$ | G | \quad \frac {R (\mathrm{U} 2 1 0 \mathrm{B})}{\overline {{R}} (\mathrm{U} 2 1 0 \mathrm{A})}. $$

When |G| ≤ 1 , U210B is set to or near its minimum resistance value of 10k , and U210A, to an equal or greater resistance. Thesituation is reversed for |G| > 1 . The 12-bit resolution of the MDACs places limitations on the values of achievable gains. ThetwoMDACstrackto within 10ppm / ^ , and thistermisthedominant one for the stability of the instrument's gain.

Similarly to the summing portion of U208, the gain amplifier (U211A) is disciplined by U207 Binorderto achieve an negligible contribution to the overall offset, offset drift, and noise. However, the error from the input bias current of U211A (which is multiplied by the resistance R (U210B)) is not negligible. ^2 A first-order cancellation of the

biasisachieved by mirroring the input current of these second half, U211B, and injecting it into the input node of U211A. Theremaining input current produces a drift term that is roughly the same as, or smaller than, the other dominant contribution to the offset stability of the instrument.

This cancellationschemeincreases thecontribution of the gain stagetothe overall noise. Thenoise current of U211 is multiplied by R(U210B) and by 2 . As R(U210B) increases linearly with the gain for |G| ≥ 1 , this terms yields 21 nV/ , referenced to the input.

The remaining noise contribution is from R(U210A) and R(U210B) . Their Johnsonnoise at the output of the staged dependence on the gain as

$$ e _ {n} \propto \sqrt {| G | (1 + | G |)}, $$

andforlargegainsisjustthenoiseofthe10kΩresistorR(U210A), referencedtotheinput.This13.5nV/ √Hztermaddsinquadrature withthe22nV/ √Hzcontributionoftheearlierthreestages,andwith thebias-currentcontribution,toyield34nV/ √Hz(f≥10kHz).At most frequencies f ≥ 100 Hz, and for |G| ≥ 1, the input-referenced noiseoftheSIM983isindependentofthegaintowithin2nV/ √Hz.

The capacitances of the analog switches ^3 that configure the variable-resistance MDAC add together at the output of the MDAC. This capacitance becomes the input capacitance of the inverting amplifier, and its value places the ultimate limit on the small signal bandwidth achievable in the gain stage and with it, in the whole instrument. The capacitancetogether with R(U210A) forms an input pole, so if the gain of the amplifier is not rolled off with a capacitor in the feedback path, the amplifier will oscillate. The amount of compensation feedback capacitanced desired for stability from oscillation increases with decreasing |G|. The compensation network consists of PFETs Q205–Q208, functioning as switches and chosen for ultralow OFF capacitance, and capacitors C208–C210. One, both, or none of C209 and C210 are inserted into the feedback path for four ranges of the gain, resulting in four possible values of the gain-bandwidth product of the stage (Pagevi). With the feedback capacitor selected, the phase margin of the amplifier improves with increasing |G|, and with the overshoot and ringing in the step response decrease.

Output voltage buffer U212 enables the instrument to drive 50 Ω loads. Comparator U215 indicates an overload at the specified output voltagelimits(Section1.2.4.2).

5.1.2.6 Output filter

The performance of the passive filter, composed of L201, R226, R227, and C211, is described on Schematic Page 2. The filter eliminates the broad-spectrum noise of high-band width amplifiers Q201, U208, and U211 beyond a few megahertz, while adding an negligible amount of overshoot in the step response.

5.1.2.7 Output microvoltmeter

The analog-to-digital converter(ADC) used for autocalibration is a part of microcontroller U107. The output signal is amplified by precision op-amp U217, then shifted by +2.5V by shunt reference D201 and fed into the ADC.

5.1.3 Front panel

Brightred7-segmentLEDdisplaysU302,U304,U306,U307,U309,U311,U313,andU314,andoverloadLEDsD301andD302aredriven byshiftregistersU301,U303,U305,U308,U310,U312,andU315.

5.2 Parts List

STANFORD RESEARCH SYSTEMS, INC.
SIM983 Scaling Amplifier Circuit Board (1 of 1) Revision D
BILL OF MATERIALS			May 5, 2006
Item	Qty.	Reference	Part	SRS P/N	Manufacturer	Manf. P/N
1	2	C101,C102	22μ T	5-00327-030	VISHAY	199D226X9035E6B1
2	10	C103,C110,C111,C205,C221,C222,C223,C224,C225,C226	10μ T	5-00098-030	VISHAY	199D106X9035D2B1
3	1	C104	330p	5-00381-100	KEMET	C1206C331J5GACTM
4	1	C105	9.0--50p	5-00106-090	XICON	24AA024
5	3	C106,C107,C108	1000p	5-00387-100	KEMET	C1206C102J1GACTM
6	5	C109,C217,C218,C219,C220	1.0μ T	5-00099-030	VISHAY	199D105X9035A2B1
7	1	C201	2.7p NP0 ±0.25p	5-00630-100	KEMET	C1206C279C5GACTM
8	2	C202,C210	3.3p NP0 ±0.25p	5-00357-100	KEMET	C1206C339C5GACTM
9	3	C203,C204,C209	1.5p NP0 ±0.25p	5-00353-100	KEMET	C1206C159C5GACTM
10	2	C206,C216	2.2μ MPE 5%	5-00584-050	PANASONIC	ECQ-E1225JFB
11	2	C207,C213	4.7μ MPE 5%	5-00073-050	XICON	146-250V4.7K
12	1	C208	0.5p NP0 ±0.25p	5-00592-100	AVX	12065A0R5C
13	1	C211	1500p NP0 5%	5-00389-100	KEMET	C1206C152J5GACTM
14	2	C212,C214	1.0μ MPE 5%	5-00245-050	WIMA	MKS4/1/63/5RM10
15	1	C215	10μ MPE 10%	5-00072-050	PANASONIC	ECQ-E1106KF

5.2PartsList5-7

Item	Qty.	Reference Part SRS P/N Manufacturer Manf. P/N
16 43	X101	,X102,X103,X104,X105, 0.1μ 5-00	299-100 KEMET C1206C104	K5RACTM
		X106,X107,X108,X109,X110,
		X111,X112,X113,X114,X115,
		X201,X202,X203,X204,X205,
		X206,X207,X208,X209,X210,
		X211,X212,X213,X214,X215,
		X216,X217,X218,X219,X220,
		X221,X301,X302,X303,X304,
		X305,X306,X307
17	2	D101,D102	BAT54S	3-00945-143	DIODES INC	BAT54S-7
18	1	D201	TL431CDBV	3-01133-123	PHILIPS	TL431CD5
19	1	D202	BAV99	3-00896-145	ON SEMI	BAV99LT1
20 2	D301	D302 Red 3-00425-060 LITEON	LTL-709E
21	1	J101	15 Pin D	1-00367-040	CINCH	DAKL-15PATI-E
22 0	J102	Header 0.100" 4×1 no part
23	1	J103	Socket 0.100" 3×2	1-00302-010	SAMTEC	CES-103-01-G-D
24	1	J104	Header 0.050" 7×2/Mixed	1-01063-109	SAMTEC	FTSH-107-04-L-M-T
25 0	J201	J202,J203 Flying	Leads no part
26	1	J301	Socket 0.050" 7×2/SM	1-01064-119	SAMTEC	FLE-107-01-G-DV-A
27	3	L101,L102,L103	FR43 bead	6-00174-051	FAIR-RITE	2643666611
28	1	L201	1.2μ 5% 500mA	6-00676-100	API DELEVAN	1210-122J
29 0	MH101	MH102,MH103,MH104 Mouning Hole no part
30	2	Q201,Q202,Q203	MMBF4416	3-01324-152	VISHAY	SST4416
31	1	Q204	MMBT2907A	3-00927-150	ON SEMI	MMBT2907ALT1
32	4	Q205,Q206,Q207,Q208	MMBF5460	3-01305-152	FSC	MMBF5460
33	5	R101,R111,R112,R115,R117	100k 5%	4-01527-100	VENKEL	CR1206-8W-104JT
34	1	R102	1.0k	4-01479-100	VENKEL	CR1206-8W-102JT
35	1	R103	210	4-01052-110	VENKEL	TRN55CF-2100TR
36	1	R104	3.9k	4-01493-100	VENKEL	CR1206-8W-392JT
37	1	R105	3.9k×4 D	4-00917-120	BI	BCN164A-392-J7
38	3	R106,R261,R314	4.7k	4-01495-100	VENKEL	CR1206-8W-472JT
39	1	R107	22k	4-01511-100	VENKEL	CR1206-8W-223JT
40	1	R108	10	4-01431-100	VENKEL	CR1206-8W-100JT
41	3	R109,R118,R119	270	4-01465-100	VENKEL	CR1206-8W-271JT
42	5	R110,R120,R121,R227,R262	100 5%	4-01455-100	VENKEL	CR1206-8W-101JT
43	3	R113,R114,R260	10k	4-01503-100	VENKEL	CR1206-8W-103JT
44	1	R116	100k×4 D 5%	4-01704-120	CTS	742C083104J
45	1	R122	150 5%	4-01459-110	VISHAY	CRCW1206151JRT1
46	1	R123	121	4-01029-110	VENKEL	TRN55CF-1210TR
47	1	R124	365	4-01075-110	VENKEL	TRN55CF-3650TR

5-8 CircuitDescription

Item	Qty.	Reference Part SRS P/N Manufacturer	Manf. P/N
48 8	R201	R219,R223,R224,R233, 1.00M 4-01405-110 VENKEL TRN55CF-1004TR
		R234,R242,R249
49	2	R202,R203	1.00k 1.0W flameproof	4-00542-000	VISHAY	CPF11K0000FKB14
50 2	R204	R205 200 1%	4-01050-110 VENKEL TRN55CF-2000TR
51	1	R206	510	4-01472-100	VENKEL	CR1206-8W-511JT
52	8	R207,R210,R211,R212,R239, R246,R253,R258	1.00k	4-01117-110	VENKEL	TRN55CF-1001TR
		R208	280	4-01064-110	VENKEL	TRN55CF-2800TR
53	1	R209	4.02k	4-01175-110 VENKEL TRN55CF-4021TR
54 1	R209	4.02k	4-01175-110 VENKEL TRN55CF-4021TR
55	1	R213	909	4-01113-110	VENKEL	TRN55CF-9090TR
56 1	R214	14.0k	4-01227-110 VENKEL TRN55CF-1402TR
57 2	R215	R222 1.000k×2 1ppm/K 0.1%rat 4-01738-122 VISHAY MPM2001AT
58 1	R216	2.500k×2 1ppm/K 0.1%rat 4-01721-122 VISHAY MPM5001AW
59	1	R217	604.0 5ppm/K	4-01733-000	VISHAY	PTF56604R00BZBF
60	1	R218	523k	4-01378-110	VENKEL	TRN55CF-5233TR
61 1	R220	49.9k	4-01230-110 VENKEL TRN55CF-4992TR
62	1	R221	10.0	4-00925-110	VENKEL	TRN55CF-10R0TR
63 1	R225	10.0k	4-01213-110 VENKEL TRN55CF-1002TR
64 1	R226	2.00k	4-01146-110 VENKEL TRN55CF-2001TR
65	1	R228	35.7 2W flameproof	4-01735-000	VISHAY	CPF235R700FKB14
66 1	R229	5.1	4-01424-100 VENKEL CR1206-8W-5R1JT
67	2	R230,R231	13.3 2W flameproof	4-01736-000	VISHAY	CPF213R300FKB14
68 3	R232	R241,R248 365k	4-01363-110 VENKEL TRN55CF-3653TR
69	1	R235	649k	4-01387-110	VENKEL	TRN55CF-6493TR
70 3	R236	R243,R250 221k	4-01342-110 VENKEL TRN55CF-2213TR
71	6	R237,R238,R244,R245,R251, R252	2.4M	4-01560-100	VISHAY	CRCW1206245JRT1
		R240,R247,R254	3.01k	4-01163-110	VENKEL	TRN55CF-3011TR
72	3	R255	392	4-01078-110	VENKEL	TRN55CF-3920TR
73	1	R256	732	4-01104-110	VENKEL	TRN55CF-7320TR
74	1	R257	249	4-01059-110	VENKEL	TRN55CF-2490TR
75	1	R259	150k 1%	4-01326-110	VENKEL	TRN55CF-1503TR
76	13	R301,R302,R303,R304,R305, R306,R307,R308,R309,R310, R311,R312,R313	4.7k×4 D	4-00911-120	BI	BCN164A-472-J7
77	13	R301,R302,R303,R304,R305, R306,R307,R308,R309,R310, R311,R312,R313
78 2	R315	R316 2.2k	4-01487-100 VENKEL CR1206-8W-222JT
79	5	S301,S302,S303,S304,S305	B3F-1052	2-00053-000	OMRON	B3F-1052
80 0	TP101	Test Point no part

5.2PartsList5-9

Item	Qty.	Reference Part SRS P/N Manufacturer	Manf. P/N
81 2	U101	U108 74HC14 3-00662-103 PHILIPS 74HC14D
82 1	U102	74HC74 3-00742-103 TI SN74HC74D
83 2	U103	U104 74HC21 3-01502-103 PHILIPS 74HC21D
84 1	U105	74AC00	3-01405-100 FSC	74AC00SC
85 1	U106	MAX6348 4.4V	3-00903-124 MAXIM	MAX6348UR44-T
86 1	U107	68HC912B32	3-01379-114 FREESCALE	MC68HC912B32CFU8
87 1	U109	LM317L	3-00096-030 ON SEMI	LM317LZ
88 1	U201	AD8510A	3-01318-120 ANALOG	AD8510AR
89 2	U202	U203 LM7121	3-01306-120 NSC	LM7121IM
90 1	U204	MAX5541C	3-01217-171 MAXIM	MAX5541CSA
91 2	U205	U207 OPA2227A	3-01471-120 TI OPA2227UA
92 1	U206	LTC1452C	3-00652-171 LTC	LTC1452CS8
93 1	U208	THS4032	3-01219-120 TI THS4032CDGN
94 1	U209	DG419	3-01367-122 VISHAY	DG419DY
95 1	U210	AD5415	3-01171-171 ANALOG	AD5415YRU
96 1	U211	EL2244	3-01300-120 INTERSIL	EL2244CS
97 1	U212	BUF634P	3-01221-120 TI BUF634P
98 3	U213	U214,U215	LM393	3-00728-121 TI LM393D
99 1	U216	MAX6225BC	3-00970-123 MAXIM	MAX6225BCSA
100	1 U217	OPA277A	3-01370-120 TI OPA277UA
101	7	U301,U303,U305,U308,U310,	74HC595A	3-00672-103	ON SEMI	MC74HC595ADT
		U312,U315
102	2	U302,U309	HDSP-A107	3-01424-061	AVAGO	HDSP-A107
103	6	U304,U306,U307,U311,U313,	HDSP-A101	3-00290-061	AVAGO	HDSP-A101
		U314
104	5	no designator	Button Cap	0-00996-999	OMRON	B32-1000
105	4	no designator	4-40x1/4 Pan Phil	0-00187-999	ACF	PPM-04C04-0-Z
106	4	no designator	#4 Split Washer	0-00096-999	J&M	4NLOCLZ
107	2	no designator	4-40x3/8 Flat Phil	0-00835-999	ACF	PUM-04C06-0-Z
108	4	no designator	4-40x1/8 Pan Slot	0-00148-999	ACF	SPM-04C02-0-Z
109	4	no designator	4-40x1/8 Pan Phil	0-00515-999	ACF	PPM-04C02-0-Z
110	8	no designator	4-40x1/8 Black Flat Phil	0-00371-999	ACF	PUM-04C03-0-B
111	6	no designator	1.5" 24AWG Uninsulated	0-00772-999	>	>
112	1	no designator	6.5" 22AWG White	0-00436-999	>	>
113	1	no designator	6.5" 22AWG Black	0-00268-999	>	>
114	1	no designator	7.5" 22AWG Red	0-00154-999	>	>
115	1	no designator	7.5" 22AWG Black	0-00161-999	>	>
116	1	no designator	3.0" 22AWG Red	0-00006-999	>	>
117	2	no designator	BNC Insulated	1-00073-256	AMPHENOL	31-10-4052
118	1	no designator	BNC	1-00003-256	TYCO	227169-4
119	1	no designator	Circuit Board	7-01639-999	FAB	SIM983 Circuit Board Rev. D
120	1	no designator	Front Panel	7-01603-999	FAB	SIM983 Front Panel Rev. B
121	1	no designator	Lexan Overlay	7-01605-999	FAB	SIM983 Front Lexan Rev. B
122	1	no designator	Rear Panel	7-01604-999	FAB	SIM983 Rear Panel Rev. A
123	2	no designator	Top/Bottom Bracket	7-00933-999	FAB	SIM Sglw. Bracket Rev. D
124	2	no designator	Module Cover	7-00932-999	FAB	SIM Module Cover Rev. C2
125	4	no designator	Rubber Foot	0-00188-999	MOUSER	5167-202
126	1	no designator	Serial Number Label	9-01545-999	FAB	SIM SN Label Rev. A

5.3 Schematic Diagrams

Circuitschematicdiagramsfollowthispage.

Electrical schematic diagram with labeled components, ICs, and wiring connections

Electrical schematic diagram with labeled components including transistors, capacitors, inductors, and control circuits.

Electrical schematic diagram of a 7-segment display driver circuit with labeled components and connections

Appendix A Index

STATUSsignal,1-2,1-7,3-12,13,3-20

signal,seeDeviceClear

Accuracy,iii,4-2

gain,seeGain,accuracy

offset,seeOffset,accuracy

verifyingatDC,4-2,4-8

Autocalibration,vii,1-2,2-2,3,3-11,3-13,3-17,3-21,4-2,5-2,5-6

Bandwidth,vi,1-2,2-3,3-6,3-10,11,4-4,5,5-2,5-5

default,1–6,3–11,3–14

Baudrate,1–9,3–6

Biascurrent,vi,4-3,5-2

Blockdiagram,1-2

BNC,iii,vi,vii,2-2

Buffer

input,3-6,3-20-22

overflow,3–6,3–22

voltage,seeInput,voltagebuffer

output,seeOutputqueue

voltage,seeOutput,voltagebuffer

Button,3-11,3-13,3-21

[gain],1-3,2-3,3-13

[offset],1-4,3-13

[polarity],1-3,4,2-3,3-13

Calibration,seeFactorycalibration

Circuitschematics,seeSchematicdiagrams

Clockstopping,1-2,2-4,3-10,3-14,5-2

Command

error,3–16,3–21

parameters,3–7,3–16

separator,3–7

terminator,3–6,7,3–14,3–17

Compensation,2-3,4-4,5-5

Consolemode,3–6,3–14,15

DB-15,1-7,8,2-2

DB-9

female,1–8

male,1–8

Defaultconfiguration,seeReset

DeviceClear,3-6,3-15,3-17,3-22

Deviceerror,3–16,3–21

Dimensions, vii

Distortion,see Totalharmonicdistortion

DS345,4-4

Error

budget,4-2

command,seeCommand,error

Executionerror,3-15,3-21

Factorycalibration,4–2,3

Firmwareerevision,3–15

Flowcontrol,1–9,3–6,3–17

Frontpanel,1-2,3,2-3,4,3-11

operation,1–3

Fullduplex,seeConsolemode

Gain,iii,vi,1-2,3,1-6,2-2,3,3-6,3-10, 11,5-4

accuracy,vi,2-3,4-3

button,seeButton,[gain]

default,1-4,1-6,3-10,3-14

polarity,seePolarity

resetting,1-4,3-13

resolution,vi,1-3,5-4

stability,vi,4-3,5-4

Gain-bandwidthproduct,vi,vii,1-2,2-3, 3-11,4-4,5-5

Gainstage,2–3,5–2,5–4

Generalinformation,iii

Ground,1-7,8,2-2,5-2

analog,1-8,2-2,5-2

chassis,1–7,8,2–2

Earth,2–2

power,1–8,2–2

star,5-2

Help,3-9

Input

capacitance,vi

connector,vi,2-2

coupling,vi

overload,seeOverload,input

resistance,vi,4–3

voltage,iii,1-8

limits,vi,vii,1-5,5-2,5-4

voltagebuffer,4–5,5–2

Interface

direct,1–7

cable,1-8

remote,seeRemoteinterface

SIM,seeSIMinterface

Inverter,5-2,5-4

Mainframe,seeSIM900

Microcontroller,5-2

Noise,vi,4-6,5-3-5

dependenceongain,4–6,5–5

verifying,4-6,4-8

Non-volatilesettings,1–6,3–6

Notation,v,3-6,3-8

Nullmodem,1–8

Offset,iii,vi,1-2-4,1-6,3-6,3-10,5-3

accuracy,vi,1-2,1-4,2-2,4-3,5-3

button,seeButton,[offset]

default,1-4,1-6,3-10,3-14

resetting,1–4,3–13

resolution,vi,1-4

settlingtime,vi,5-3

stability,vi,4-3,5-2-4

voltagelimits,vi,1–4

Offsetgenerator,5-2,3

Output

connector

front,vi,2-2

rear,vi,2-2

current,vi,1-2,2-2

filter,5-2,5-5

maximumload,1-2,2-2,5-5

overload,seeOverload,output

resistance,vi,2–2

voltage,iii,1-8

limits,vi,1-5,2-3,5-5

maximumundistortedsinewave,1-2, 2-3

voltagebuffer,5–5

Outputqueue,3–6,3–15,3–21,22

Overload,1-2,1-4,2-4,3-14,4-2

input,vii,1-2,1-5,3-14,3-22,5-2

OVLDindicator,1-2,1-5,5-6

inputplusoffset,vii,1–5,3–14,3–23,5–4

output,vii,1-2,1-5,3-14,3-23,5-5

OVLDindicator,1-2,1-5,5-6

Overshoot,4-4,5-5

Parity,1–9,3–6,3–17,3–21

Parts,5–6

Polarity,vi,1-2-4

button,seeButton,[polarity]

Power

analog,5–2

ground,seeGround,power

requirements,vi,1–7,8

Power-on,1-6,2-4,3-6,3-13,3-15,3-

17,3-20-23

Preparationforuse,iii

Querycommand,3-7,3-16,3-20

Rearpanel,1–2,3

Registers,seeStatus,registers

Remoteinterface,vii,1-2,1-6,2-4,3-1, 3-6,3-9,3-14

dataformat,3–10,11

Reset,1-6,2-3,3-13-15,3-17

Risetime,4–4

RS-232,1-2,1-8,3-6,3-17,3-21,22,5- 2

settings,1–9,3–17

Safety,iii

Schematicdiagrams,5–9

Self-test,3–15

Serialinterface,seeRS-232

Serialnumber,3–15

Service,iii,4-3

Setcommand,3-7,3-16

Settlingtime,seeBandwidth

offset,seeOffset,settlingtime

SIM900,iii,1-2,1-7,8,2-2,3-6

SIM928,4-2

SIM965,4-6

SIM970,4-2,3

SIMinterface,vii,1-7,3-20 connector,1-7,2-2,5-2

Slewrate,vi,2-3,4-5,5-2

Specifications,vi

SR785,4-4,4-6

Stability gain,seeGain,stability offset,seeOffset,stability

Status,3–11,3–19 registers,3–11,3–19 CESE,3–12,3–22 CESR,3–6,3–12,3–20–22 ESE,3–12,3–14,3–21 ESR,3–6,3–12,3–15,3–20 OLSB,3–20 OLSE,3–13,14,3–23 OLSR,3–13,14,3–22,23 SB,3–12,3–20–23 SRE,3–12,3–14,3–20

Stepresponse,4–4,5,5–5

Stickybits,3–19,20

Summingamplifier,5–2,3

Temperature, vi, 2–2, 4–2

Token,3–7,3–15,16 mode,3–14,3–17

Totalharmonicdistortion(THD),vi,4–6

Warmup,vii,2-2,4-2

Weight,vii