SIM914 - Unknown SRS - Free user manual and instructions

USER MANUAL SIM914 SRS

350 MHz Preamplifier

SIM914

Stanford Research Systems

Certification

StanfordResearchSystemscertifiesthatthisproductmetitspublishedspecificationsatthetime ofshipment.

Warranty

ThisStanfordResearchSystemsproductiswarrantedagainstdefectsinmaterialsandworkmanshipforaperiodofone(1)yearfromthedateofshipment.

Service

Forwarrantyserviceorrepair, thisproductmustbereturnedtoaStanfordResearchSystems authorizedservicefacility.ContactStanfordResearchSystemsoranauthorizedrepresentative beforereturningthisproductforrepair.

Informationinthisdocumentissubjecttochangewithoutnotice.

Copyright ©StanfordResearchSystems, Inc., 2003, 2006. Allrightsreserved.

StanfordResearchSystems, Inc.

1290-DReamwoodAvenue

Sunnyvale, CA94089USA

Phone:[phone]•Fax:[phone]

www.thinkSRS.com•e-mail:[e-mail]

PrintedinU.S.A.Documentnumber9-01546-903

Contents

1Operation1-1

1.1 Description....1-2
1.2Operation....1-3
1.3SIMInterfaceConnector....1-3
1.4Specifications....1-5

2Calibration2-1

2.1General....2-2
2.2RequiredEquipment....2-2
2.3HighFrequencyCompensation....2-2
2.4OffsetCalibration....2-3
2.5GainCalibration....2-3

3CircuitDescription3-1

3.1 InputStage .... 3-2
3.2OutputStage....3-2
3.3OverloadDetection....3-2
3.4Power....3-3
3.5PartsList....3-4
3.6SchematicDiagrams....3-5

1 Operation

TheSIM914isatwo-channel,350MHz,DC-coupledamplifier. This chapterprovidesgeneralinstructionsonitsuse.

In This Chapter

1.1Description....1-2
1.2Operation....1-3
1.3SIMInterfaceConnector....1-3
1.3.1 Grounding....1-3
1.3.2DirectInterfacing....1-4
1.4Specifications....1-5

1.1 Description

TheSIM914isatwo-channel,350MHzbandwidth,DC-coupled, 50 Ω amplifier with a gain of 5× (+14 dB). The two channels may be cascadedforagainof25×(+28dB).TheunitusesBNCconnectors forinputsandoutputs(seeFigure1.1).ArearpanelDB-15connector providespowertotheunit.

SRS SIM914 Dual 350 MHz Preamp ON CHANNEL 1 OVLD IN 50 Ω × 3 OUT 50 Ω CHANNEL 2 OVLD IN 50 Ω × 3 OUT 50 Ω SIM914 DUAL 350 MHz PREAMP S/N SRS MADE IN U.S.A

Figure1.1:TheSIM914frontandrearpanels.

Thefullscaleinputis±200mV. Theinputnoise(above1kHz) is typically5.2nV/ √Hz. Theoutputislinearover±1Vandshouldbe terminatedintoa50Ωload. Outputriseandfalltimesare1.3ns. Theoutputwillrecoverfroma10×full-scaleoverloadwithin3ns. Theunitisprotectedfrom±50V,1μsinputoverloads.

TheSIM914ispoweredby±5VDCfromtheSIM900Mainframe. TherearethreeLEDsonthefrontpanel.ThegreenLEDindicates thatpowerispresent.TheredLEDsindicatethattheoutputsignal forthecorrespondingchannelisoutsideitslinearrange,typically ±1.3VDC.Briefoverloads(<5ns)triggera10msflashandwillset theoverloadstatusbitinthemainframe.

1.2 Operation

TheSIM914istypicallyinstalledintheSIM900Mainframe,which canaccommodateuptoeightSIM914s(plusoneremoteunit.)The unitison,asindicatedbythefront-panelPowerLED,whenever the mainframehaslinepowerandisturnedon.

The input impedance for each channel is 50 . The DC input voltage must be limited to ±4V to avoid damaging the amplifier front-end. The amplifier is internally protected from 50 V transient of 1 s duration. The 50 input impedance is intended to terminate 50 coaxial cables such as RG-58.

The amplifiers perform well when cascaded due to their high input return loss and flat frequency response characteristics. Referenced to the input, the broadband noise (1Hz to 300MHz) is 80 Vrms. Peak-to-peak noise is typically 5 times the rms value. This corresponds to about 10mVppat the output of two cascaded amplifiers, 50mVppat the output of three cascaded amplifiers, and 250mVppat the output of four cascaded amplifiers.

1.3 SIM Interface Connector

TheDB-15SIMInterfaceConnectorprovidespowerandoverload monitoringtotheinstrument. Theconnectorsignalsarespecified in thetablebelow.

PinNameDescription
1	SIGNALGNDGround
2	-STATUS	Overload (TTL output, active low)
6	-5V	Powersupply
8	PSRTN	Ground
9	CHASSISGNDChassisground
13	+5V	Powersupply

Table1.1: SIMInterfaceConnectorpinassignments, DB-15. All other pins are left unconnected on the SIM914.

1.3.1 Grounding

IntheSIM914, all threegroundlines(Pins1,8&9) are tied common to the chassis, and also form the signal ground.

1.3.2 Direct Interfacing

The primary connection to the SIM914 Amplifier is therear-panel DB-15SIM interface connector. Typically, the SIM914 is mated to a SIM900 Mainframe viathis connection, either through one of the internal Mainframeslots, or theremotecable interface.

ItisalsopossibletooperatetheSIM914directly, without using the SIM900Mainframe. Thissectionprovidesdetailsontheinterface.

CAUTION

TheSIM914hasnointernalprotectionagainstreversepolarity,missing supply,orovervoltageonthepowersupplypins.Misapplicationofpower maycausecircuitdamage.SRSrecommendsusingtheSIM914together withtheSIM900Mainframeformostapplications.

ThematingconnectorneededisastandardDB-15receptacle,such asAmppart#747909-2(orequivalent).Clean,well-regulatedsupplyvoltagesof±5VDCmustbeprovided,with+5Vsuppliedon Pin13and−5VsuppliedonPin6(seeTable1.1).Groundmaybe providedonanycombinationofPins1,8or9.The−STATUSsignal maybemonitoredonPin2foralow-goingTTL-compatibleoutput indicatinganamplifieroverloadcondition.

1.4 Specifications

Inputs (50 Ω source)		MinTypMax		Units
	Input signal level	-200		+200	mV
	Impedance4	9.55050	5Ω
	Returnloss32dB
	Offset	-500+50	0μV
	Offsetdrift	-10+10μV/			°C
	Biascurrent(note1)310μA
	Protection (DC)	-4		+4	VDC
	Protection(1μstransient)-50+50V
	Recoverytime(10×FSoverload)3		ns
	Noise(10Hz)22nV/				√Hz
	Noise(100Hz)		8.6		nV/√Hz
	Noise (>1 kHz)		5.2		nV/√Hz
	Noise(1Hzto300MHzBW)80μVrms
	Crosstalk(CH1outtoCH2in)-61dB
	Crosstalk(CH2outtoCH1in)-82dB
Amplifier	Gain(note2)4.9	55.005.0	5V/V
	Bandwidth(-3dB)		350		MHz
	Rise/falltime		1.3		ns
	Propagationdelay		2.7		ns
Outputs (into 50 Ω)	Source impedance	49.5	50	50.5	Ω
	Linear operation	-1.0		+1.0	V
	Overload level	-1.3		+1.3	V
	Limit level	-1.6		+1.6	V
General	NumberofChannels2
	Operatingtemperature	0		40	°C
	Weight		1.4		Ibs
	Power		±5		VDC
	Supplycurrent80mA
	Dimensions	1.5"W×3.6"H×7.0"D

Notes:

1. The input bias current flows out of the unit, creating a positive offset of about 150 V on the 50 input termination. This offset will be affected by the DC impedance of the source that is connected to the input.
2. Amplifier gain is calibrated by applying a known current to the input and measuring the voltage into a high impedance load. The gain is adjusted so that a 1 mA source applied to the input produces a 500 mV voltage at the unloaded output.

2 Calibration

ThischapterdescribeshowtoadjusttheSIM914foroptimumperformance. Themoduleshouldbewarmedupforatleast15minutes beforemakinganyadjustments.

In This Chapter

2.1General....2-2
2.2RequiredEquipment....2-2
2.3HighFrequencyCompensation......2-2
2.4OffsetCalibration....2-3
2.5GainCalibration....2-3

2.1 General

The purpose of calibration is to verify operation of the unit and to:

• Adjust the high frequency compensation for best pulse response.
• AdjusttheoffsettonulltheDCvoltageattheoutputwithno input.
• Adjust the gainto 10 × for an unloaded output so that the nominal gain for an amplifier driving a 50 Ω load will be 5 × (+14dB).

Sinctheadjustmentsareinterdependent,itisimportantthatthe adjustmentsbedoneintheprescribedorder,andthatallofhead-justmentsbedone.Forexample,adjustingthehighfrequencycompensationwillaffecttheoutputoffset.

2.2 Required Equipment

1. Pulsegenerator, splitter and attenuator to toproduce ± 100 mV square waves with a time of less than 1 ns. (DG535 Digital Delay / Pulse Generator, AB output, intounmatched teedriving two 50 Ω cables with a 20 dBattenuator on the one that goesto the SIM914.)
2. Digitalmultimeter with 4-wireohm measurement capability (Agilent34401).
   3.Oscilloscopewithatleast300MHzbandwidth.

2.3 High Frequency Compensation

TheSIM914usesanAD8009currentfeedbackamplifierintheoutputstage. ThegainoftheamplifieriscontrolledbytheratioofresistorsinthefeedbacknetworkandthebandwidththiscontrolledbytheTheveninequivalentsourceimpedanceofthefeedbacknetwork. Theratioisfixed(byR115&R116orR215&R216)toprovideagainof5×andthesourceimpedancemaybeadjusted(byP102andP202).

Thebandwidthissettooptimize the pulseresponse of the amplifier. This is done by applying a fast pulse at the input and adjusting P102 (or P202 for Channel 2) so that the output risetime and overshoot most closely match their risetime and overshoot of the fast input pulse as observed on a 300 MHz oscilloscope with 50 Ω input impedance.

NotethatadjustingP102willaffecttheoffsetforChannel1,asthere isalargeinputbiascurrent(150μAmax)totheinvertinginputof

theAD8009.TheoffsetwillneedtobeadjustedaftertheHFcompensationisadjusted.

1. Splitthepulse output from the DG535 (setto1V amplitude) withacoaxtee. Takeonecable from the etechannel of the oscilloscope (setto50Ω input termination) and the other tothetop channel of the SIM914 via a20dB coaxial attenuator.
2. AdjustP102(Channel1"HFCOMP"pot)tomatchtheoutput risetimeandovershoottotheinputrisetimeandovershoot.
3. RepeatforChannel2, adjusting the pulseresponse with P202.

2.4 Offset Calibration

The outputoffsetisaffected by the HFcompensation and so the offset should be culled after the HFcompensation is adjusted. The offset may also be affected by the amplifier gain adjustment if there is a large input of offset voltage.

1. Leavetheinputsunconnected.
2. Connecttheoutput(withouta50Ωload)totheDMMonthe millivoltDCrange.
3. AdjustP101(Channel1 "OFFSET" pot) tonulltheoutputvoltage.
4. Verify that the output voltageshifts down by less than 2.5 mV when a 50 Ω terminator is placed on the input. (The voltage shift V_out = 10 × i_b × R_s , where i_b is the input bias current, and R_s is the change in input source impedance, here 25 Ω. This confirms that the input bias current i_b < 10 A .)
   5.Repeattheproceduretonulltheoutputof Channel2byadjustingP201.

2.5 Gain Calibration

The overall gain of the amplifier is 5× when driving a 50 Ω load and 10× when driving a high impedance. The inputs are to the amplifier typically acurrent source (such as the output from a photomultiplier tube) and so that magnitude of the input resistance is included in the gain calibration by measuring the transimpedance. (Calibration is done with a current source as an input while measuring the voltage at the output.)

ADMMused inthe4-wireresistancemodeisconvenient forperformingthecalibration. TypicallyaDMMwillmeasuresmallresistancesbymeasuringthevoltageacrosstheresistorwhilepassinga

1mADCcurrentthroughtheresistor.Wemeasurethegainofthe amplifierbymeasuringthevoltageattheoutputwhileapplyingtest currenttoinput.Whenthegainisproperlyadjusted,1mAapplied tothe50Ωinputgenerates50mVattheinputand500mVatthe (unterminated)outputcausingtheDMMtoindicatea"resistance" of500Ω.(ToavoidautorangingconfusionbytheDMM,a453Ω resistorisplacedinserieswiththecurrentsource.)

SincetheDMMusesaDCcurrentasthetestsource,itisimportant thattheamplifieroffsetbenulledpriortoperformingtheDCgain adjustment.

1. Setup the DMMinthe4-wireresistance measurement mode.
2. Apply the current output to the Channel1 input via a 453Ω in-lineresistor.
3. Apply the unterminated Channel1 output to the DMMs4-wire sense input.
4. AdjustP100(Channel1 "GAIN" pot) so that the DMM indicates a "resistance" of 500Ω.
5. Verify that the offset was nulled by connecting the current source from the DMM to the input of the other channel and measuring a resistance of less than 1 .
6. Repeat the gain adjustment for Channel2 by adjusting P200.

3 Circuit Description

ThischaptergivesageneraldiscussionofthecircuitryintheSIM914.

Thetwoamplifierchannelsareidentical. Thisdescriptionusesreferencedesignatorsinthetopchannel, Channel1.

In This Chapter

3.1 InputStage....3-2
3.2OutputStage....3-2
3.3OverloadDetection....3-2
3.4Power....3-3
3.5PartsList....3-4
3.6SchematicDiagrams....3-5

3.1 Input Stage

The inputisterminated into 50Ω by the parallel combination of R100 & R101. The input signal is coupled via a 47Ω resistorto the high speed "clamp-amp," U100. U100 is configured as anon-inverting gain 2× amplifier. Pins 8 & 5 on U100 define input clamping threshold sof ± 0.31V. If the input signal exceeds the threshold then U100 will us the clamping thresholds as inputs, thereby limiting the output to ± 0.62V. This prevent the output of U100 from over-driving then next gain stage.

Inputsignalsinexcessof±1.4Vareshuntedtogroundviatheinput protectiondiodesD100&D101.NormallyboththediodesinD100 are reversed biased and so they donot interferewith the signal. The diodesinD101 are forward biased by R103&R104. When the input signale exceeds ± 1.4V (7 × the full scale input), one of the diodesin D100 will beg into conduct, thereby limiting the input to U100 to a safe level.

ThegainofU100canbeadjustedby±10%byP100,whichiscalibratedatthefactorytosettheoverallgainofthechannelto5×when terminatedintoa50Ωload.TheoutputofU100ispassedtothenext gainstageviaR112,a47Ωresistor.

3.2 Output Stage

Thenextstagehasafixedgainof5×withanadjustableoffsetand adjustablehighfrequencyresponse.ThegainofU101issetbyR115 &R116.Theoffset,adjustedbyP101andinjectedbyR117,isnulled atthefactory. ThehighfrequencyresponseofU101isaffectedby thesourceimpedanceofitsinputsignalanditsfeedbacknetwork. TurningP102clockwisedecreasesthesourceimpedanceofthefeedbacksignalandincreasesthehighfrequencyresponseofthegain stage.P102isadjustedatthefactoryforanoptimumpulseresponse providingatypical-3dBbandwidthof350MHz.

The output from U101 is passed to the front-panel output BNC via the parallel resistors R118 & R119, providing a 50 Ω output impedance. These resistors, in combination with the 50 Ω load resistor(providedbytheuser), attenuatethesignal by 2× so that the overall gain is 5×.

3.3 Overload Detection

Overloadsaredetectedattheoutputofthesecondgainstage,U101. ApositiveoverloadisrectifiedbyD102andchargesC107.AnegativeoverloadisrectifiedbyD102anddischargesC106.Oneofthe

comparatorsinU102willbedrivenlowwhenthevoltageonC106or C107exceeds±1.7V. ThedrivencomparatordischargesC108from +5 V to -5 V. C108 will be slowly recharged to +5 V by R128, a 1MΩresistor,therebystretchingtheoverloadsignaltoabout10ms. OneofthecomparatorsinU300drivesthefront-paneloverloadLED untilthevoltageonC108rechargesaboveground.Thisoverloaddetectionwilldetectoverloadsasshortas3ns.

Theoverloaddetectorsarewire-ordbyD303whichwillpullthestatuspin(pin2ontherear-panelconnectortotheSIMmainframe)to0Vviathe3.9VZenerdiodewhenanoverloadoccurs.Thestatus pinmaybepolledviatheSIM900Mainframetodetectoverloadsin theunit.

3.4 Power

The±5VDCpowersuppliesarefilteredattherearpanel(byL1,L3,C1&C2),againonthemainPCB(byL2,L4,C300&C301),andfinallyateachchanneloftheamplifier(L100,L101,C110&C111forthetopchannelandL200,L201,C210&C211forthebottomchannel.)Carefulpowersupplyfilteringisimportanttoreducechannelcrosstalk.ThecrosstalkfromtheoutputofChannel1totheinputofChannel2islessthan-60dB(1:1000oftheamplitude)andpeaksaround300MHz.ThecrosstalkfromtheoutputofChannel2totheinputofChannel1islessthan-80dB(1:10,000oftheamplitude)andoccursinabroadbandbetween180MHzand360MHz.

3.5 Parts List

Qnt Reference SRS P/N Part Qnt Reference SRS P/N Part

8 C1,C2,C110,C111,C210, 5-00472 4.7U-35T 2 J303,J304 mounting 0-00259 4-40X1/2PP
	C211,C300,C301 3 J305,J306,J307 mounting		0-00241 4-40X3/16 PP
5	C3,C106,C107,C206,C207	5-00375	100P	2	J303,J304 mounting	0-00042 4-40 HEX
12	C100,C101,C102,C103,C104,C105,C200,C201,C202,C203,C204,C205	5-00299	.1U	2	J303,J304 mounting	0-00043 4-40 KEP
				2 DB-15 mounting		0-00835 4-40X3/8PF
				4 Front panel mounting		0-00148 4-40X1/8,PS
2	C108,C208	5-00298	.01U	4	Rear panel mounting	0-00515 4-40X1/8PP
1	D1	3-01429	MMBZ5228B	8	Module Cover Mounting	0-00371 4-40X3/16P
6	D100,D101,D102,D200,D201,D202	3-00896	BAV99L	1	Front Panel, SIM914	7-00987
				1 Lexan FP Overlay, SIM914 7-01353
1 D300		3-00424 LED-G 1 Rear Panel, SIM914 7-01410
2	D301,D302	3-00425	LED-R	2	SIM 1X BRACKET	7-00933
1	D303	3-00649	MBAW56L	2	SIM Module Cover	7-00932
1	J1	1-00367	DB15-GND	4	Foot	0-00188 SR550FOOT
4 J100,J101,J200,J201		1-00003	BNC
1 J311 TO J312		1-00483 Jumper 4X1 (2")
1 J2-J5		1-01042 Jumper 4X1 (4")
8 L1,L2,L3,L4,L100,L101,L200,L201		6-00236 BEAD
2 P100,P200		4-00487	20
2 P101,P201		4-00011	10K-10T
4 R103,R104,R203,R204		4-01503	10K
2 P102,P202		4-00353	100-10T
9 R1,R105,R107,R121,R125R205,R207,R221,R225		4-01455	100
4 R2,R300,R307,R308		4-01479	1K
12	R100,R101,R109,R110,R118,R119,R200,R201,R209,R210,R218,R219	4-01021	100/1%
4 R102,R112,R202,R212		4-01447	47
8 R106,R108,R122,R123,R206,R208,R222,R223		4-01134 1.50K
2 R115,R215		4-01050	200/1%
2 R116,R216		4-01280	49.9
2 R117,R217		4-01213 10.0K
4 R120,R124,R220,R224		4-01527	100K
4 R126,R127,R226,R227		4-01163 3.01K
2 R128,R228		4-01551	1M
2 U100,U200		3-00897	AD8037
2 U101,U201		3-00898	AD8009
3 U102,U202,U300		3-00728 LM393
1 PCB		7-00967	SIM914 Rev C

3.6 Schematic Diagrams

Schematicdiagramsfollowthispage.

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