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Operation and Service Manual

BJT Preamp

SIM911

Stanford Research Systems

Revision 2.1

May 8, 2007

Summary of Contents for BJT SIM911

Page 1: ...Operation and Service Manual BJT Preamp SIM911 Stanford Research Systems Revision 2 1 May 8 2007...

Page 2: ...must be 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 th...

Page 3: ...tput 1 5 1 4 SIM Interface 1 6 2 Remote Operation 2 1 2 1 Index of Common Commands 2 2 2 2 Alphabetic List of Commands 2 3 2 3 Introduction 2 4 2 4 Commands 2 5 2 5 Register Model 2 9 3 Performance Te...

Page 4: ...ii Contents SIM911 BJT Preamp...

Page 5: ...ct grounding com WARNING ponent failure and excessive common mode input voltages are ex amples of conditions in which the instrument may expose the subject to large input currents Therefore Stanford R...

Page 6: ...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 s...

Page 7: ...e instructions WARNING are not obeyed A caution means that damage to the instrument or other equipment CAUTION is possible Front panel buttons are set as Button Adjust is shorthand for Adjust Adjust F...

Page 8: ...A B GND Input coupling AC or DC Input shields Floating or ground Maximum input differential 1 V before overload Maximum input common mode 5 V clamped at 6 V Maximum output voltage 10 V before overloa...

Page 9: ...necessary information to get started quickly with the SIM911 In This Chapter 1 1 Instrument Overview 1 2 1 2 Front Panel Operation 1 2 1 2 1 Gain 1 3 1 2 2 Offset 1 3 1 2 3 Overload 1 3 1 2 4 Inputs 1...

Page 10: ...liminated by only clocking the microprocessor when settings are being changed The complete amplifier configuration i e gain settings coupling etc is saved in non volatile memory The front end amplifie...

Page 11: ...g Gain or Gain in the GAIN block on the upper right of the module The change is reflected in the LEDs to the left of the buttons Pushing Gain when on gain 100 produces no effect Pushing Gain when on g...

Page 12: ...The maximum signal voltage is 1 V while the maximum common mode voltage is 5 V Exceeding these limits will cause OVLD to light up When the Ground input is selected the user inputs A B are left floatin...

Page 13: ...e output and the SIM interface connector see Figure 1 2 The rear panel output is wired in parallel to the front panel output The output is not designed to drive 2 simultaneous 50 loads If one output i...

Page 14: ...d in Table 1 1 Direction Pin Signal Src Dest Description 1 SIGNAL GND MF SIM Ground reference for signal 2 STATUS SIM MF Status service request GND asserted 5 V idle 3 RTS MF SIM HW Handshake 5 V talk...

Page 15: ...the PC TXD directly to TD and similarly RTS RTS and CTS CTS In other words a null modem style cable is not needed To interface directly to the DB 9 male DTE RS 232 port typically found on contemporary...

Page 16: ...d Power Ground are tied through protection schot tky diodes and can therefore not be more than 0 35 V apart These two ground lines should be separately wired back to a single low impedance ground sour...

Page 17: ...Commands 2 3 2 3 Introduction 2 4 2 3 1 Power on configuration 2 4 2 3 2 Buffers 2 4 2 3 3 Device Clear 2 4 2 4 Commands 2 5 2 4 1 Command syntax 2 5 2 4 2 Notation 2 5 2 4 3 Examples 2 5 2 4 4 Amplif...

Page 18: ...rameter for set commands illegal for queries Amplifier RST 2 6 Reset GAIN i 2 6 Gain COUP i 2 6 Coupling INPT i 2 6 Input SHLD i 2 6 Shield Status STB 2 7 Status Byte SRE i 2 7 Service Request Enable...

Page 19: ...8 Identify RST 2 6 Reset SRE i 2 7 Service Request Enable STB 2 7 Status Byte TST 2 8 Self Test C CONS i 2 8 Console Mode COUP i 2 6 Coupling G GAIN i 2 6 Gain I INPT i 2 6 Input O OVLD 2 7 Overload...

Page 20: ...oldface 2 3 2 Buffers Incoming data from the host interface is stored in a 32 byte input buffer Characters accumulate in the input buffer until a command terminator either hCRi or hLFi is received at...

Page 21: ...hout any surrounding characters are always required Do not send or as part of the command Multiple parameters are separated by commas Commands are ter minated by either hCRi or hLFi characters Null co...

Page 22: ...ounded shield floated RST Example Gain GAIN i Set query the amplifier gain to i 1 2 5 10 20 50 100 GAIN Example 50 Coupling COUP i Set query the amplifier input coupling COUP 1 sets AC coupling while...

Page 23: ...le Status Monitors Overload STOL i Set query the Status Monitors Overload mode to i 0 1 STOL 1 causes the STATUS signal pin 2 on J401 Dsub 15 connec tor to become a real time monitor of the amplifier...

Page 24: ...N VER where is the 6 digit serial number and is the firmware revision level IDN Example Stanford Research Systems SIM911 s n003654 ver2 10 Self Test TST Query the device self test The SIM911 does not...

Page 25: ...es it to be cleared Weight Bit Flag 1 0 EXE 2 1 CMD 4 2 QRE 8 3 OVR 16 4 SERR 32 5 URQ 64 6 DCAS 128 7 OVLD EXE Execution Error Indicates an error in a command that was successfully parsed Out of rang...

Page 26: ...n the SRE corresponds one to one with a bit in the SB register and acts as a bitwise AND of the SB flags If any bits are simultaneously set in both the SB and the SRE then a service request is indicat...

Page 27: ...he module should be warmed up for at least 15 minutes before making any adjustments In This Chapter 3 1 Offset 3 2 3 2 Calibration 3 2 3 2 1 Adjusting the CMRR 3 2 3 2 2 Adjusting the gain 3 2 3 2 3 A...

Page 28: ...be running for at least 15 minutes before doing any adjustments 3 2 1 Adjusting the CMRR The common mode adjustment minimizes the common mode re sponse of the amplifier by balancing the two sides of t...

Page 29: ...requency at the test point 2 5 MHz 3 3 Performance Tests The following curves are typical noise density vs frequency for the SIM911 10 0 10 1 10 2 10 3 10 4 10 5 1 10 Frequency Hz Voltage Noise nV Hz...

Page 30: ...ommunication connector pin specifications 3 4 SIM911 Performance Test Record Description Measured Value Serial Number Clock Frequency at TP401 Gain 1 Gain 2 Gain 5 Gain 10 Gain 20 Gain 50 Gain 100 CMR...

Page 31: ...911 circuit design A complete parts list and circuit schematics are included In This Chapter 4 1 Circuit Discussion 4 2 4 1 1 Input amplifier and protection circuitry 4 2 4 1 2 Programmable gain stage...

Page 32: ...cision divider ladders R201 R204 and R207 R211 provide programmable gain steps without introducing excessive noise at lower gains Gain allocations are noted on the schematic indicating which switches...

Page 33: ...art time of the RC oscillator ensures that incoming se rial data will be correctly decoded by the microcontroller s UART even when the clock is started by the serial start bit of the incoming data Whe...

Page 34: ...D515 R241 4 00988 45 3 D508 3 00425 LEDRED R301 R316 R402 R405 R407 4 01527 100K D514 D513 3 00426 YELLOW R409 R410 R415 J101 J102 J201 J202 1 00003 BNC R314 R401 R406 R408 R417 4 01503 10K J301 1 00...

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