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1.2

Front-Panel Operation

1 – 3

1.2.1

Inputs

Each of the four input channels of the SIM980 has a front-panel block
consisting of the BNC input connector, a control button, and several
LED indicators.

1.2.1.1

Polarity toggle

Each input can be switched between inverting or non-inverting po-
larity by

briefly

pressing that channel’s control button. When invert-

ing, the

−

LED is illuminated; when non-inverting,

+

is lit. Note

that the polarity is always displayed, independent of whether that
channel is on or o

ff

.

1.2.1.2

On/Off toggle

Each input can independently be turned on or o

ff

by

holding

that

channel’s control button for

∼

1.5 seconds. When on, the channel is

either added to or subtracted from the output (depending on polarity,
section 1.2.1.1). When o

ff

, it does not contribute to the output signal

at all. The

OFF

LED is lit to indicate when a channel is o

ff

.

Unused channels should be turned o

ff

rather than simply left un-

connected, as the Johnson noise of the open 1 M

Ω

input resistor will

dominate the output noise of the SIM980.

1.2.1.3

Offset autocalibration

The SIM980 uses an active input o

ff

set correction to trim all input

circuitry as well as the summing circuitry of DC o

ff

sets. The user

can initiate an autocalibration cycle by disconnecting all inputs and
outputs from the SIM980, and pressing and holding any of the con-
trol buttons for

∼

5 seconds. The entire process takes approximately

1 minute, and is completed when the relays have stopped “clicking”
for at least 10 seconds.

Note that it is important that all inputs be open (or, preferably, shorted
to ground) before initiating an o

ff

set autocalibration cycle. If any

input channel is above

∼

500

µ

V amplitude, the SIM980 will reject the

autocalibration request.

1.2.1.4

Input Overload

Each of the four input channels of the SIM980 has an overload de-
tection circuit. The input is considered overloaded when the signal
magnitude exceeds

±

10 V. This is indicated by the red

OVLD

LED at

the top of each front-panel block.

SIM980

Analog Summing Amplifier

Содержание SIM980

Страница 1: ...Operation and Service Manual Analog Summing Amplifier SIM980 Stanford Research Systems Revision 1 9 August 28 2006...

Страница 2: ...returned to a Stanford Research Systems authorized service facility Contact Stanford Research Systems or an authorized representative before returning this product for repair Information in this docu...

Страница 3: ...ex of Common Commands 2 2 2 2 Alphabetic List of Commands 2 4 2 3 Introduction 2 6 2 4 Commands 2 6 2 5 Status Model 2 17 3 Performance Tests 3 1 3 1 Introduction 3 2 3 2 Tools and preparation 3 2 3 3...

Страница 4: ...ii Contents SIM980 Analog Summing Amplifier...

Страница 5: ...fier for combining multiple analog signals from DC to 1 MHz Service Do not install substitute parts or perform any unauthorized modifi cations to this instrument The SIM980 is a single wide module des...

Страница 6: ...d 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 O...

Страница 7: ...s manual are Front panel buttons are set as Button Adjust is shorthand for Adjust Adjust Front panel indicators are set as Overload Remote command names are set as IDN Literal text other than command...

Страница 8: ...r 5 min warm up Input range 10 V before overload Output range 10 V before overload Input slew rate 40 V s Total Harmonic Distortion 0 01 80 dB max 1 kHz Output slew rate 75 V s Operating temperature 0...

Страница 9: ...y with the SIM980 Summing Amplifier In This Chapter 1 1 Introduction to the Instrument 1 2 1 1 1 Overview 1 2 1 1 2 Power on State 1 2 1 2 Front Panel Operation 1 2 1 2 1 Inputs 1 3 1 2 2 Output 1 4 1...

Страница 10: ...inverting or non inverting operation or switched off Each input is 1 M and DC coupled and accepts signals between 10 V 1 1 2 Power on State The SIM980 stores its operation state input channel configur...

Страница 11: ...an simply left un connected as the Johnson noise of the open 1 M input resistor will dominate the output noise of the SIM980 1 2 1 3 Offset autocalibration The SIM980 uses an active input offset corre...

Страница 12: ...es details on the interface The SIM980 has no internal protection against reverse polarity missing CAUTION supply or overvoltage on the power supply pins Misapplication of power may cause circuit dama...

Страница 13: ...by directly connecting the appropriate interface lines from the SIM980 DB 15 plug to the RS 232 serial port of a personal computer 1 Connect RXD from the SIM980 directly to RD on the PC TXD directly t...

Страница 14: ...F 3 7 RTS 4 8 CTS 10 3 TxD 11 2 RxD 5 Computer Ground to P S 7 15 VDC 13 5 VDC 14 15 VDC 8 9 Ground P S return current 1 Signal Ground separate wire to Ground Table 1 2 SIM980 Direct Interface Cable...

Страница 15: ...mples 2 8 2 4 4 Amplifier Commands 2 9 2 4 5 Autocalibration Commands 2 10 2 4 6 Serial Communication Commands 2 11 2 4 7 Status Commands 2 11 2 4 8 Interface Commands 2 13 2 5 Status Model 2 17 2 5 1...

Страница 16: ...bration OFST i j 2 10 Offset Value Serial Communications FLOW z 2 11 Flow Control PARI z 2 11 Parity Status STB i 2 11 Status Byte SRE i j 2 11 Service Request Enable CLS 2 12 Clear Status ESR i 2 12...

Страница 17: ...2 1 Index of Common Commands 2 3 LBTN 2 15 Button TOKN z 2 15 Token Mode TERM z 2 16 Response Termination SIM980 Analog Summing Amplifier...

Страница 18: ...libration ARMC z 2 10 Arm Autocalibration C CESE i j 2 12 Comm Error Status Enable CESR i 2 12 Comm Error Status CHAN i j 2 9 Channel Control CONS z 2 14 Console Mode F FLOW z 2 11 Flow Control L LBTN...

Страница 19: ...2 2 Alphabetic List of Commands 2 5 T TERM z 2 16 Response Termination TOKN z 2 15 Token Mode SIM980 Analog Summing Amplifier...

Страница 20: ...host interface is stored in a 64 byte input buffer Characters accumulate in the input buffer until a command terminator either hCRi or hLFi is received at which point the mes sage is parsed and execut...

Страница 21: ...of the command Multiple parameters are separated by commas Multiple commands may be sent on one command line by separating them with semi colons so long as the input buffer does not overflow Commands...

Страница 22: ...et and query forms 2 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 SIM980 are set as straight teletype...

Страница 23: ...AN 2 1 CHAN 0 1 1 0 0 Read Offset Voltage READ i Query the output voltage in tenths of microvolts When the offset autocalibration circuitry is active an internal high gain amplifier is activated to mo...

Страница 24: ...flag is set see ARMC above an ACAL command will initiate an offset autocalibration cycle The entire process takes be tween 30 s and 90 s and should ideally be performed only after the SIM980 has been...

Страница 25: ...on modules default to PARI NONE PARI EVEN Example 2 4 7 Status Commands The Status commands query and configure registers associated with status reporting of the SIM980 Status Byte STB i Reads the St...

Страница 26: ...e ESE i j Set query the Standard Event Status Enable Register bit i to j ESE 6 1 Example ESE 64 Comm Error Status CESR i Query Comm Error Status Register for bit i Upon executing a CESR query the retu...

Страница 27: ...set any new service request will only pulse the STATUS signal low for a minimum of 1 s The default behavior is to latch STATUS low until a STB query is received At power on PSTA is set to OFF PSTA Ex...

Страница 28: ...xample Console Mode CONS z Set query the Console mode to z OFF 0 ON 1 CONS causes each character received at the Input Buffer to be copied to the Output Queue At power on and Device Clear CONS is set...

Страница 29: ...en 12 Bad token value 13 Bad hex block 14 Unknown token IDN Example LCME 4 The error 4 Illegal set is due to the missing Button LBTN Query the channel number of the last button pressed A query of LBTN...

Страница 30: ...2 CRLF 3 LFCR 4 The htermi sequence is appended to all query responses sent by the module and is constructed of ASCII character s 13 car riage return and 10 line feed The token mnemonic gives the seq...

Страница 31: ...rs These read write registers define a bitwise mask for their cor responding event register If any bit position is set in an event register while the same bit position is also set in the enable regist...

Страница 32: ...gister has become true IDLE Indicates that the Input Buffer is empty and the command parser is idle Can be used to help synchronize SIM980 query responses ESB Event Status Bit Indicates whether one or...

Страница 33: ...2 QYE 8 3 DDE 16 4 EXE 32 5 CME 64 6 URQ 128 7 PON OPC Operation Complete Set by the OPC command INP Input Buffer Error Indicates data has been discarded from the Input Buffer QYE Query Error Indicat...

Страница 34: ...g each asynchronous bit period window HWOVRN Hardware Overrun Set when an incoming serial data byte is lost due to internal processor latency Causes the Input Buffer to be flushed and resets the comma...

Страница 35: ...Output The output of the summing amplifier is overloaded output voltage exceeds 10 V Note that the output can overload with out any input channel overloading and vice versa 2 5 8 Overload Status OVSR...

Страница 36: ...2 22 Remote Operation SIM980 Analog Summing Amplifier...

Страница 37: ...ction 3 2 3 2 Tools and preparation 3 2 3 3 Precalibration Values 3 2 3 3 1 Offset Voltages 3 2 3 3 2 Calibration Words 3 3 3 3 3 DC Gain Match 3 3 3 3 4 AC Gain Match 3 3 3 4 Calibration 3 4 3 4 1 Of...

Страница 38: ...essible after removing the right side panel It is easier to calibrate the module by connecting it through a cable to the SIM extension port but the calibration can also be performed with the module lo...

Страница 39: ...oltage as V 2 Calculate the gain ratio mismatch as V 1 V 2 V 1 V 2 1 100 and record this value as the DC mismatch 3 3 4 AC Gain Match Using the same 1 to 4 splitter from section 3 3 3 connect all four...

Страница 40: ...minute wait for relays to cease switching for at least 10 seconds The output voltage will fluctuate during cal ibration but settle to less than 20 V Verify that the calibration words are within the v...

Страница 41: ...ccord ing to section 3 3 3 and record the results 3 4 3 AC Gain Calibration The SIM980 amplifier bandwidth rolls off around 6 MHz This is ac complished with a combination of fixed capacitors and one t...

Страница 42: ...he matching for the others This can be accomplished best by driving the two channels with the same signal and operating one in positive and the other one in negative mode while using R268 and C217 to...

Страница 43: ...d results General Name Serial Number Date Time Offset Voltage Output V Channel 1 V Channel 2 V Channel 3 V Channel 4 V Calibration Words OFST 1 OFST 2 OFST 3 OFST 4 OFST 5 OFST 6 Gain DC mismatch AC m...

Страница 44: ...3 8 Performance Tests SIM980 Analog Summing Amplifier...

Страница 45: ...A complete parts list and circuit schematics are included In This Chapter 4 1 Circuit Descriptions 4 2 4 1 1 Input circuitry 4 2 4 1 2 Summing circuitry 4 2 4 1 3 Output circuitry 4 2 4 1 4 Offset me...

Страница 46: ...olled by relays K201 K208 A combination of two dual pole dual throw relays per channel allows enable disable and polarity change with constant noise gain and signal bandwidth The difference amplifier...

Страница 47: ...erter U403 to minimize any input and the output offset voltage Chopper amplifier U404 is switched off dur ing normal operation to eliminate the potential noise generated by its internal chopping circu...

Страница 48: ...4 01308 97 6K J103 1 00302 Socket 0 100 3x2 R404 4 01310 102K J201 J206 1 00003 BNC R406 4 01348 255K JS201 1 01079 20 pin R407 4 01526 91K JS301 1 01080 20 Pin R408 4 01517 39K K201 K208 3 01492 ASX...

Страница 49: ...4 3 Schematic Diagrams 4 5 4 3 Schematic Diagrams Schematic diagrams follow this page SIM980 Analog Summing Amplifier...

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