SRS Labs Lock-In Amplifier Manuale Utente

MODEL SR530LOCK-IN AMPLIFIER1290-D Reamwood AvenueSunnyvale, CA 94089 U.S.A.Phone: (408) 744-9040 • Fax: (408) 744-9049Email: [email protected] • www.

6Phase Controls Adjust phase in smoothly accelerating 0.025° steps, or by90° steps. Press both 90° buttons to zero the phase.Reference LCD Display ref

7Abridged Command ListAX Auto offset XAY Auto offset YAR Auto offset RAP Auto phaseB Return Bandpass Filter StatusB0 Take out the Bandpass FilterB1 Pu

8Status Byte Definition Bit Meaning 0 Magnitude too small to calculate phase 1 Command Parameter is out-of-range 2 No detectable reference

9SR510 Guide to OperationFront PanelThe front panel has been designed to be almostself-explanatory. The effect of each keypress isusually reflected i

10Dynamic Reserve Sensitivity RangeLOW 1 µV through 500 mVNORM 100 nV through 50 mVHIGH 100 nV through 5 mVDynamic ReserveThe dynamic reserve (DR) is

11display CH1 X setting output expand? offset? (RCOSØ) X X+Xofst yes yes X+Xofst XOFST Xofst yes yes Xofst R R+Rofst yes yes X+Xofst R OFST

12to ON) sets the offset to the previously enteredvalue.If an attempt is made to advance the offset valuebeyond full scale, the ON LED will blink. An

13possible. If R is less than 0.5% of full scale, thephase output defaults to zero degrees.The Phase Output may not be expanded and theOFFSET keys do

14down, the offset advances in larger and largerincrements, the largest increment being 10% of fullscale. When the offset is turned OFF the appliedof

15going transitions of the reference input. Thismode triggers on a negative pulse train or on thefalling edges of a TTL type pulse train(remembering

16should be allowed to approach a steady valuebefore a reading is taken. For the 1 Hz ENBW,this time is on the order of 15 to 30 seconds; forthe 10 H

17SR530 Guide to OperationRear PanelAC PowerThe ac line voltage selector card, line fuse, andline cord receptacle are located in the fuse holderat the

18the REF OUTPUT on the rear panel to the REFINPUT on the front panel. The REF OUTPUT is a1 Vrms sine wave. The SINE OUTPUT may beused as the stimul

19SR530 Guide toProgrammingThe SR530 Lock-in Amplifier is remotelyprogrammable via both RS232 and GPIBinterfaces. It may be used with laboratorycompu

20The REM LED is on whenever the SR530 isprogrammed to be in the remote state.RS232 Echo and No EchoOperationIn order to allow the SR530 to be operate

21SR530 Command ListThe leading letters in each command sequencespecify the command. The rest of the sequenceconsists of parameters. Multiple parame

2223 200 mV24 500 mVNote that sensitivity settings below 100 nV areallowed only when a pre-amplifier is connected.HThe H command reads the pre-amplifi

23If n is included, then v may be sent also. v is theoffset value up to plus or minus full scale in unitsof volts. For example, to offset half of fu

24X n {,v}n designates one of the 6 general purpose analogports located on the rear panel. If n is 1,2,3, or 4,the X command will return the voltage

25characters again.ResetThe Z command resets the unit to its default state.The default front panel settings are listed in theDEFAULTS section of the G

iTable of ContentsCondensed InformationSAFETY and Preparation for use 1Symbols 2Specifications 3Front Panel Summary 5Abridged Command List 7Status Byt

266) Answers are coming back from the SR530too slowly due to the W6 default setting forthe character interval time. Use the Wcommand to speed up the

27DC1 Device Clear capabilityRL0 REN,LLO, GTL not implemented.'I' command sets Remote-Local.SR530 Response to GPIB CommandsMnemonic Command

28The Lock-in Technique The Lock-in technique is used to detect and measure very small ac signals. A Lock-in amplifier can make accurate measureme

29Vpsd1 = Vs cos(wrt) cos(wst+Ø) = 1/2 Vs cos[(wr + ws)t+Ø] + 1/2 Vs cos[(wr - ws)t+Ø] Vpsd2 = Vs sin(wrt) cos(wst+Ø) = 1/2 Vs sin[(wr

30In the first method, the lock-in uses the A input in a'quasi-differential' mode. Here, the lock-in detectsthe signal as the voltage betwee

31attenuated by 6 dB/octave more. You may wish touse the bandpass filter and select a low dynamicreserve setting in order to achieve a better outputs

32SR530 Block DiagramSeveral new concepts are used to simplify thedesign of SR530 lock-in amplifier. In addition toimplementing recent advances in li

33The Signal ChannelThe instrument has both current and voltageinputs. The current input is a virtual ground, andthe 100 MΩ voltage inputs can be use

34Circuit DescriptionIntroductionThe SR530 Lock-in amplifier is an integratedinstrument combining state of the art analog designwith advanced micropro

35U204, and U205 are analog switches which selectthe feedback capacitors for the 5 decades ofoperation. The two halves of U202 are matchedtransconduc

iiCircuit DescriptionIntroduction 34Signal Amplifier 34Current Amplifier 34Notch Filters 34Bandpass Filter 34Reference Oscillator 35PSD, LP Filters an

36U419. Analog switch U418 selects the time constantand gain. The full scale output of U418 is 5 volts.The quadrature demodulator and low pass ampli

37or, generates the gate pulse during which referencepulses are counted.I/O addresses are decoded by U705, U706, andU707. The microprocessor controls

38Calibration and Repair This section details calibration of the instrument. Calibration should be done only by a qualified electronics technician

39The CMRR is adjusted by the single turn potentiometer located at A1 under the single hole at the front of the signal shield. (The shield is the a

40Appendix A:Noise Sources and CuresNoise, random and uncorrelated fluctuations ofelectronic signals, finds its way into experimentsin a variety of wa

41Capacitive Coupling. A voltage on a nearbypiece of apparatus (or operator) can couple to adetector via a stray capacitance. AlthoughCstray may be

42Resistive Coupling (or 'Ground Loops').Currents through common connections can giverise to noise voltages.Resistive CouplingHere, the dete

43Appendix B:Introduction to the RS232The 'RS232' is a standard for bit serialasynchronous data communication. Thestandard defines the form

44baud.) The typical data string 5.1270<cr> has 7 characters, requiring 4 msec to be sent. Stop Bits Generally, selection of 2 stop bits wi

45Appendix C:Introduction to the GPIBThe IEEE-488 Standard specifies the voltagelevels, handshake requirements, timing,hardware details, pinout and co

1Safety and Preparation for Use***CAUTION***: This instrument may be damaged if operated with the LINE VOLTAGE SELECTOR set forthe wrong applied ac in

46Appendix D:Program ExamplesAll of the program examples which follow do thesame thing, only the computer, language, orinterface is changed. The prog

47Program Example 2:IBM PC, Microsoft Fortranv3.3, via RS232Machine language routines to interface to theCOM1: RS232 port are provided in the fileRS2

48call rxstr(str2)[ convert string variable into real variable v1 and v2read (str1,1000) v1read (str2,1000) v21000 format (bn,f10.0)[ print results t

49Program Example 3:IBM PC, Microsoft C v3.0,via RS232Machine language routines to interface to theCOM1: RS232 port are provided in the fileRS232.OBJ

50txstr (″q2$″); /* read channel 2 output */rxstr (str2); /* into str2 */sscanf (str2, ″%f″, &v2); /* scan str2 for a float variable */x += 0.0025

51Program Example 4:IBM PC,Microsoft Basic,via GPIBThis program requires the Capital EquipmentCorporation GPIB card for the IBM PC or XT. Ithas firmw

52390 ′400 PRINT “CH1 = ″;V1; ″ CH2 =″;V2410 ′420 X = X + .0025 ′INCREMENT X6 OUTPUT BY 2.5 MV430 IF X>10 THEN X 0 ′RESET RAMP440 X$ = X6$ + STR$(

53Program Example 5:HP85 via GPIBThis program provides an example of an HP85 program using the GPIB interface which could be used tocontrol the lockin

54Documentation This section contains the parts lists and schematics for the SR530 lock-in amplifier. The first digit of any part number can be us

SR530 COMPONENT PARTS LIST55Oscillator Board Parts ListREF. SRS part# VALUE DESCRIPTIONC 1 5-00023-529 .1U Cap, Monolythic Ceramic, 50V, 20%, Z5UC 2 5

2

SR530 COMPONENT PARTS LIST56Main Board Parts ListREF. SRS part# VALUE DESCRIPTIONBR1 3-00062-340 KBP201G/BR-81D Integrated Circuit (Thru-hole Pkg)BR2

SR530 COMPONENT PARTS LIST57REF.SRS part# VALUE DESCRIPTIONC 214 5-00059-512 .47U Cap, Stacked Metal Film 50V 5% -40/+85cC 215 5-00060-512 1.0U Cap, S

SR530 COMPONENT PARTS LIST58REF.SRS part# VALUE DESCRIPTIONC 410 5-00056-512 .1U Cap, Stacked Metal Film 50V 5% -40/+85cC 411 5-00056-512 .1U Cap, Sta

SR530 COMPONENT PARTS LIST59REF.SRS part# VALUE DESCRIPTIONC 802 5-00012-501 330P Capacitor, Ceramic Disc, 50V, 10%, SLC 803 5-00012-501 330P Capacito

SR530 COMPONENT PARTS LIST60REF.SRS part# VALUE DESCRIPTIONCY1 6-00010-620 4.000 MHZ CrystalD 101 3-00004-301 1N4148 DiodeD 102 3-00004-301 1N4148 Dio

SR530 COMPONENT PARTS LIST61REF.SRS part# VALUE DESCRIPTIONR 102 4-00033-404 100M Resistor, Carbon Comp, 1/4W, 5%R 103 4-00030-401 10 Resistor, Carbon

SR530 COMPONENT PARTS LIST62REF.SRS part# VALUE DESCRIPTIONR 162 4-00188-407 4.99K Resistor, Metal Film, 1/8W, 1%, 50PPMR 163 4-00035-401 10M Resistor

SR530 COMPONENT PARTS LIST63REF.SRS part# VALUE DESCRIPTIONR 307 4-00040-401 13K Resistor, Carbon Film, 1/4W, 5%R 308 4-00193-407 499 Resistor, Metal

SR530 COMPONENT PARTS LIST64REF.SRS part# VALUE DESCRIPTIONR 359 4-00045-401 2.0K Resistor, Carbon Film, 1/4W, 5%R 360 4-00032-401 100K Resistor, Carb

SR530 COMPONENT PARTS LIST65REF.SRS part# VALUE DESCRIPTIONR 433 4-00021-401 1.0K Resistor, Carbon Film, 1/4W, 5%R 501 4-00022-401 1.0M Resistor, Carb

3SR530 Specification SummaryGeneralPower 100, 120, 220, 240 VAC (50/60 Hz); 35 Watts MaxMechanical 17" x 17" x 5.25" (Rack Mount Includ

SR530 COMPONENT PARTS LIST66REF.SRS part# VALUE DESCRIPTIONR 703 4-00027-401 1.5K Resistor, Carbon Film, 1/4W, 5%R 705 4-00021-401 1.0K Resistor, Carb

SR530 COMPONENT PARTS LIST67REF.SRS part# VALUE DESCRIPTIONU 118 3-00130-340 5532A Integrated Circuit (Thru-hole Pkg)U 201 3-00087-340 LF347 Integrate

SR530 COMPONENT PARTS LIST68REF.SRS part# VALUE DESCRIPTIONU 415 3-00126-335 51A05 RelayU 416 3-00084-340 ICL7650 Integrated Circuit (Thru-hole Pkg)U

SR530 COMPONENT PARTS LIST69REF.SRS part# VALUE DESCRIPTIONU 807 3-00110-340 MC1489 Integrated Circuit (Thru-hole Pkg)U 808 3-00078-340 DS75160A Integ

SR530 COMPONENT PARTS LIST70REF.SRS part# VALUE DESCRIPTIONZ 0 0-00257-000 HANDLE3 Hardware, Misc.Z 0 0-00371-026 4-40X3/16PF Screw, Black, All TypesZ

SR530 COMPONENT PARTS LIST71REF.SRS part# VALUE DESCRIPTIONDS611 3-00012-306 GREEN LED, RectangularDS612 3-00012-306 GREEN LED, RectangularDS613 3-000

SR530 COMPONENT PARTS LIST72REF.SRS part# VALUE DESCRIPTIONDS662 3-00012-306 GREEN LED, RectangularDS663 3-00012-306 GREEN LED, RectangularDS664 3-000

SR530 COMPONENT PARTS LIST73REF.SRS part# VALUE DESCRIPTIONRN603 4-00226-425 150X9 Resistor Network SIP 1/4W 2% (Common)RN604 4-00222-425 150X7 Resist

SR530 COMPONENT PARTS LIST74REF.SRS part# VALUE DESCRIPTIONC 1006 5-00058-512 .33U Cap, Stacked Metal Film 50V 5% -40/+85cC 1007 5-00049-566 .001U Cap

SR530 COMPONENT PARTS LIST75REF.SRS part# VALUE DESCRIPTIONP 1103 4-00016-445 10K Pot, Multi-Turn, Side AdjustP 1104 4-00016-445 10K Pot, Multi-Turn,

4Acquisition Time 25 Sec at 1 Hz6 Sec at 10 Hz2 Sec at 10 kHzSlew Rate 1 decade per 10 S at 1 kHzPhase Control 90° shiftsFine shifts in 0.025° stepsP

SR530 COMPONENT PARTS LIST76REF.SRS part# VALUE DESCRIPTIONR 1109 4-00022-401 1.0M Resistor, Carbon Film, 1/4W, 5%R 1110 4-00217-408 1.000K Resistor,

SR530 COMPONENT PARTS LIST77REF.SRS part# VALUE DESCRIPTIONU 1102 3-00091-340 LF412 Integrated Circuit (Thru-hole Pkg)U 1103 3-00090-340 LF411 Integra

SR530 COMPONENT PARTS LIST78

5Front Panel SummarySignal Inputs Single Ended (A), True Differential (A-B), or Current (I)Signal Filters Bandpass: Q-of-5 Auto-tracking filter (In or