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2 – 4

Description of Operation

stage amplifies its input voltage noise by the factor

5

of (1

+

R

F

/

R

source

)

,

where

R

source

is the source resistance. This noise adds in quadrature

with the current noise of the stage.To prevent the voltage noise term
from dominating the overall output noise, set the current gain to

R

F

.

R

source

.

2.2

Bias and Ground

2.2.1

Grounds

The output of the SIM918 is referenced to ground. To maintain
the DC accuracy of the instrument, there are two separate ground
references. Power Ground (Pin 8 of the SIM interface connector)
provides a current return path for digital control signals, power-
intensive analog amplifiers, and the power supplies. Signal Ground
(Pin 1 of the interface connector) serves as the reference point for
analog voltages. The outer shell of the Output BNC connector is tied
to Signal Ground. The output current of the preamplifier returns
to the power supply through Signal Ground. When

INPUT Shield

GND

is selected, the shell of the Input BNC is also tied to Sig-

nal Ground.

The outer shells of the rear-panel Shield Program Voltage and
Ref Clock Sync BNCs are connected to chassis ground, Pin 9 of the
DB–15 SIM interface connector. The separate power, signal, and
chassis grounds are

not

directly connected within the preamplifier.

When operating in the SIM900 Mainframe, the three grounds are
tied together inside the mainframe, and through the mainframe
to the Earth. The signal and power grounds are connected inside
the SIM918 through back-to-back Schottky diodes, so they cannot be
more than

∼

±

0

.

35 V apart.

2.2.2

Bias

The bias potential is received by an ultralow-o

ff

set voltage bu

ff

er. It

is this bu

ff

ered voltage that appears on the shield of the Input BNC

when

INPUT Shield Bias

is selected.

The shield of the Bias connector is not used as a reference for the
bias voltage. When

Bias Shield GND

is selected, the shield is at

Signal Ground. The limits on the bias voltage in Section 1.2.4.1
are relative to this ground. A voltage exceeding these limits by
more than 1 V will be clamped , through diodes, to

±

5

.

5 V relative to

Power Ground. The 10 M

Ω

input resistor is connected between Bias

and Signal Ground.

5

At frequencies low enough that the resistive components of the two impedances
are dominant.

SIM918

Precision Current Preamplifier

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Содержание SIM918

Страница 1: ...Operation and Service Manual Precision Current Preamplifier SIM918 Stanford Research Systems Revision 1 8 December 13 2006 ...

Страница 2: ...e 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 document is subject to change without notice Copyright c Stanford Research Systems Inc 2006 All rights reserved Stanford Research Systems Inc 1290 D Reamwood Avenue Sunnyvale CA 94089 USA Phone 408 744 9...

Страница 3: ... 1 9 1 6 SIM Interface 1 10 2 Description of Operation 2 1 2 1 About Transimpedance Amplifiers 2 2 2 2 Bias and Ground 2 4 2 3 Output 2 5 2 4 Autozero Trim 2 5 2 5 Phase Locked Loop 2 6 2 6 Autocalibration 2 6 2 7 Clock Stopping 2 7 2 8 Quiescent Operation 2 8 3 Remote Operation 3 1 3 1 Index of Common Commands 3 2 3 2 Alphabetic List of Commands 3 4 3 3 Introduction 3 6 3 4 Commands 3 7 3 5 Statu...

Страница 4: ...ii Contents SIM918 Precision Current Preamplifier ...

Страница 5: ...he outer shield of the front panel Input coaxial BNC connector in the SIM918 can be switched to the rear panel Program input If a dangerous voltage is applied to the Program terminal it may be present on the outer shell of the Input connector and may cause injury or death Do not exceed 60 volts to the Earth at the center terminal of the rear panel WARNING Shield Program Voltage BNC connector Do no...

Страница 6: ...is cable is connected to the curent input of the SIM918 the stored charge may damage the front end JFET To avoid this problem provide a leakage path of about 100 kΩ to ground inside the base of the PMT to prevent charge accumulation Service Do not install substitute parts or perform unauthorized modifications to this instrument Preparation for use The SIM918 is a single wide module designed to be ...

Страница 7: ...General Information v SIM918 Precision Current Preamplifier ...

Страница 8: ...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 SIM918 Precision Current Preamplifier ...

Страница 9: ...IN GAIN is shorthand for GAIN GAIN Front panel indicators are set as OVLD Signal names are set as STATUS Signal levels are set as HIGH Remote command names are set as IDN Literal text other than command names is set as OFF Special ASCII characters are set as hCRi Remote command examples will all be set in monospaced font In these examples data sent by the host computer to the SIM918 are set as str...

Страница 10: ...5 106 V A 130 fA Hz 107 V A 42 fA Hz 108 V A 15 fA Hz Voltage noise 1 4 25 µV rms 3 dB bandwidth 5 106 V A 22 kHz 107 V A 12 kHz 108 V A 4 kHz Terminals Isolated BNC 6 BNC shield Ground bias program open Bias input Selection On ground Voltage 7 5 0 5 0 V Resistance 10 MΩ 3 dB bandwidth 0 2 Hz Terminals Isolated BNC 6 BNC shield Ground float Program input Voltage 60 60 V Resistance 3 GΩ Terminals G...

Страница 11: ...ce Higher values of source capacitance or a finite source resistance will degrade these specifications 6 Amphenol 31 10 4052 or similar 7 An overload will be detected and the instrument is not guaranteed to perform properly if these limits are exceeded or if Vbias iin RF exceeds the limits Continuous application of a bias voltage Vbias in excess of 15 V will damage the instrument 8 Tyco 227169 4 o...

Страница 12: ...x General Information SIM918 Precision Current Preamplifier ...

Страница 13: ...1 2 1 1 3 Cabling and grounding 1 3 1 1 4 Autocalibration 1 3 1 1 5 Remote interface and status 1 3 1 1 6 Block diagram 1 4 1 1 7 Front and rear panels 1 5 1 2 Front Panel Operation 1 5 1 2 1 Gain 1 5 1 2 2 Autozero 1 5 1 2 3 Input 1 7 1 2 4 Bias 1 7 1 2 5 Output overload 1 8 1 3 Connections 1 8 1 4 Power On 1 9 1 5 Restoring the Default Configuration 1 9 1 6 SIM Interface 1 10 1 6 1 SIM interface...

Страница 14: ... necessary to keep the offset voltage at zero The autozero feature can be engaged or inhibited remotely or from the front panel giving the user flexibility in sensitive applications With autozero inhibited the preamplifier retains microvolt input accuracy for many hours When engaged it takes the autozero only a few cycles of a reference clock to restore the offset to within its specified limits Th...

Страница 15: ...maximum flexibility for cabling and ground ing The input connection can be opened and the bias voltage can be connected to signal ground The shield of the Input BNC can be switched between signal ground the bias voltage or the rear panel Program input which can be left floating if desired With the Program input a user can supply an excitation potential to an experiment via the shield conductor of ...

Страница 16: ...the overload or unlocked condition 1 1 6 Block diagram The output of the main amplifier transimpedance stage is refer enced to the bias voltage A difference amplifier subtracts the bias voltage so the output of the instrument is directly proportional to the input current iin and the gain RF Vout Vbias iin RF Vbias iin RF 1 1 A block diagram of the preamplifier is shown below in Figure 1 1 LPF 0 5 ...

Страница 17: ... effect If GAIN is pressed when RF 100 V µA the press has no effect A simultaneous press of GAIN has a special meaning This press initiates autocalibration Section 2 6 1 2 2 Autozero 1 2 2 1 Engaging the autozero circuit The autozero circuit is turned ON by the press of a front panel button There will be a pause of up to 3 3 seconds a wait for a positive going edge of the reference clock At the en...

Страница 18: ...acquisition time ically takes 250 s just over 4 minutes to acquire a lock The yel low Unlocked LED is illuminated whenever the SIM918 is not in a locked state For further discussion of locking see Chapter 2 5 For the duration of an unlocked state the switches in the autozero circuit are not guaranteed to have correct duty cycles Therefore the specified input offset accuracy is not guaranteed while...

Страница 19: ...nter terminal of the Bias BNC and the signal ground of the instrument If the bias source is set to ground the green BIAS GND light is on With Bias grounded the difference amplifier Figure 1 1 is switched out and the output of the instrument is taken directly from the trans impedance stage With this configuration there is no common mode error and the output offset error is reduced When Bias is conn...

Страница 20: ...raw output of the transimpedance stage Vbias iin RF exceeds these limits To distinguish between the two output over load possibilities use the OVLD query The overload LED stays on for a minimum of 50 ms after this time it turns off if the overload condition has ceased 1 3 Connections There are five BNC connectors in the SIM918 three on the front panel and two at the rear Panel BNC Terminal Signal ...

Страница 21: ...efault Configuration The default configuration of the SIM918 is 1 Gain 106 V A 2 Autozero on 3 Input connected 4 Input shield at ground 5 Bias at ground 6 Bias shield at ground 7 Reference clock direction is input 8 The phase locked loop Section 2 5 is inactive when autozero is off To reset the module into this configuration turn the SIM900 Main frame power on while holding a front panel button of...

Страница 22: ...connection in SIM918 6 5V MF SIM Power supply no connection in SIM918 7 15V MF SIM Power supply 8 PS RTN MF SIM Power ground 9 CHASSIS GND Chassis ground 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 SIM918 13 5V MF SIM Power supply 14 15V MF SIM Power supply 15 24V MF SIM Power supply no connecti...

Страница 23: ...a null modem style cable is not needed To interface directly to the DB 9 male DTE RS 232 port typically found on contemporary personal computers a cable must be made with a female DB 15 socket to mate with the SIM918 and a female DB 9 socket to mate with the PC s serial port Separate leads from the DB 15 need to go to the power supply making what is sometimes know as a hydra cable The pin connecti...

Страница 24: ...ower Ground are connected through back to back Schottky diodes so they cannot be more than 0 35 V apart The three ground lines should be sepa rately wired to a single low impedance ground source at the power supply 1 6 2 2 Serial settings The initial serial port settings at power on are baud rate 9600 8 bits no parity 1 stop bit and no flow control The baud rate of the SIM918 cannot be changed Flo...

Страница 25: ...hapter 2 1 About Transimpedance Amplifiers 2 2 2 1 1 Input capacitance and stability 2 2 2 1 2 Choosing the right gain 2 3 2 2 Bias and Ground 2 4 2 2 1 Grounds 2 4 2 2 2 Bias 2 4 2 3 Output 2 5 2 4 Autozero Trim 2 5 2 5 Phase Locked Loop 2 6 2 6 Autocalibration 2 6 2 7 Clock Stopping 2 7 2 8 Quiescent Operation 2 8 2 1 ...

Страница 26: ...plifier of the SIM918 Precision Current Preamplifier is a transimpedance amplifier based on a composite JFET input design 2 1 1 Input capacitance and stability The input impedance of JFET devices is extremely large However the impedance experienced as a whole by a current input to the feedback amplifier i e the change in the input voltage1 divided by the input current has two other much more signi...

Страница 27: ...ance in parallel with the effective inductance can form a resonant tank circuit if the capacitance is large enough that the resulting resonant frequency lies within the bandwidth of the transimpedance amplifier The SIM918 has adequate compensation feedback capacitance to prevent oscillation for up to 100 pF of ad ditional input capacitance 4 To avoid a feedback oscillation follow these steps 1 Pla...

Страница 28: ...ar panel Shield Program Voltage and Ref Clock Sync BNCs are connected to chassis ground Pin 9 of the DB 15 SIM interface connector The separate power signal and chassis grounds are not directly connected within the preamplifier When operating in the SIM900 Mainframe the three grounds are tied together inside the mainframe and through the mainframe to the Earth The signal and power grounds are conn...

Страница 29: ...nt panel The output signal is filtered by a passive LRC with f 3 dB 25 kHz The filter eliminates broad spectrum noise while adding a negligi ble amount of overshoot in the step response The R in the filter contributes to the output resistance The output difference amplifier when engaged Bias not at GND introduces an offset error that can be greater than the maximum input offset error of the preamp...

Страница 30: ...e PLL oscillator runs freely generating a 1 0 Hz square wave with rising edges at the beginning of each autozero half cycle The voltage controlled oscillator in the loop operates at 240 Hz for 60 Hz power line frequency FPLC and at 200 Hz for FPLC 50 Hz The PLL can be automatically inhibited and the voltage controlled oscillator turned off when the reference clock is External and au tozero is off ...

Страница 31: ... 2 If an external reference clock is detected the autocalibration terminates immediately with LDDE 2 Autocalibration does not affect gain accuracy 2 7 Clock Stopping The microprocessor clock of the SIM918 stops if the module is idle freezing the digital circuitry The following actions wake up the clock 1 A power on 2 A press of a front panel button 3 Activity send or receive at the remote interfac...

Страница 32: ...clock transitions 1 Reset the preamplifier Section 1 5 2 Set Input to Open 3 Wait for at least 40 s 4 Turn autozero off 5 Select the desired gain 6 Close the input 7 Perform the measurement After this sequence is complete the control output of the autozero circuit holds at a value that initially drives the input offset within its specification Without active autozeroing the input offset may drift ...

Страница 33: ... 5 Configuration commands 3 11 3 4 6 Calibration commands 3 14 3 4 7 Status commands 3 16 3 4 8 Interface commands 3 19 3 4 9 Serial communication commands 3 22 3 5 Status Model 3 24 3 5 1 Status Byte SB 3 25 3 5 2 Service Request Enable SRE 3 25 3 5 3 Standard Event Status ESR 3 26 3 5 4 Standard Event Status Enable ESE 3 26 3 5 5 Communication Error Status CESR 3 26 3 5 6 Communication Error Sta...

Страница 34: ...m 3 12 Gain INPT z 3 12 Input BIAS z 3 12 Bias SHLD y z 3 13 Shield CHOP z 3 13 Autozero SYNC z 3 13 Reference Clock Direction FREQ 3 13 Reference Clock Frequency PHAS 3 14 Autozero Phase APLL z 3 14 Keep PLL Active Calibration ACAL 3 14 Autocalibration READ m 3 15 Read Microvoltmeter OFST m j 3 15 Offset Trim Status CLS 3 16 Clear Status STB i 3 16 Status Byte SRE i j 3 16 Service Request Enable ...

Страница 35: ... 3 18 Overload RCLK 3 19 Reference Clock State Interface RST 3 19 Reset IDN 3 20 Identify TST 3 20 Self Test OPC 3 20 Operation Complete CONS z 3 20 Console Mode LEXE 3 21 Execution Error LCME 3 21 Command Error LDDE 3 22 Device Error TOKN z 3 22 Token Mode TERM z 3 22 Response Termination Serial Communications PARI z 3 23 Parity SIM918 Precision Current Preamplifier ...

Страница 36: ... Self Test A ACAL 3 14 Autocalibration APLL z 3 14 Keep PLL Active AWAK z 3 11 Keep Clock Awake B BIAS z 3 12 Bias C CESE i j 3 17 Communication Error Status Enable CESR i 3 17 Communication Error Status CHOP z 3 13 Autozero CONS z 3 20 Console Mode F FPLC j 3 12 Power Line Cycle Frequency FREQ 3 13 Reference Clock Frequency G GAIN m 3 12 Gain H HELP 3 10 Instrument Help I INPT z 3 12 Input L LBTN...

Страница 37: ...8 Overload P PARI z 3 23 Parity PHAS 3 14 Autozero Phase PSTA z 3 18 Pulse STATUS Mode R RCLK 3 19 Reference Clock State RCSE i j 3 17 Reference Clock Status Enable RCSR i 3 17 Reference Clock Status READ m 3 15 Read Microvoltmeter S SHLD y z 3 13 Shield SYNC z 3 13 Reference Clock Direction T TERM z 3 22 Response Termination TOKN z 3 22 Token Mode SIM918 Precision Current Preamplifier ...

Страница 38: ... power line frequency FPLC 2 The gain 3 Autozero on off 4 Input selection on open 5 Input shield selection program bias ground 6 Bias selection on ground 7 Bias shield selection float ground 8 Whether or not the phase locked loop stays active when au tozero is off 9 Calibration values Upon power on those settings are restored to their values before the power was turned off Where appropriate the de...

Страница 39: ...ce specifies the command The rest of the sequence consists of parameters Commands may take either set or query form depending on whether the character follows the mnemonic Set only commands are listed without the query only commands show the after the mnemonic and optionally query commands are marked with a Parameters shown in and are not always required Parameters in are required to set a value a...

Страница 40: ...y its corresponding integer value For ex ample to set the response termination sequence to hCRi hLFi the following two commands are equivalent TERM CRLF or TERM 3 For queries that return token values the return format keyword or integer is specified with the TOKN command SIM918 Precision Current Preamplifier ...

Страница 41: ...l parameter for both set and query forms 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 SIM918 are set as straight teletype font while responses received by the host computer from the SIM918 are set as slanted teletype font The usage examples vary with respect to set query optional parame ters and tok...

Страница 42: ...equired the brackets themselves should not be sent General commands HELP Send this text AWAK z Keep the module clock awake Configuration commands FPLC j Power line rejection frequency 50 60 GAIN m Set query gain INPT z Input OPEN CLOSE BIAS z Bias GND ON SHLD y z Shield INPUT BIAS GND BIAS FLOAT PROG CHOP z Autozero OFF ON SYNC z Reference clock IN OUT FREQ Reference clock frequency Hz PHAS Switch...

Страница 43: ...known state IDN Identify TST Does nothing OPC Operation complete CONS z Console OFF ON LEXE Last Execution Error LCME Last Communications Error LDDE Last Device Error TOKN z Turn token mode OFF ON TERM z Cmd line end NONE CR LF CRLF LFCR Serial interface command baud rate is always 9600 PARI z Parity NONE EVEN ODD MARK SPACE Keep Clock Awake AWAK z Set query the SIM918 keep awake mode to z OFF 0 O...

Страница 44: ...put terminal to the output of the transimpedance stage through RF 20 kΩ This state is indicated by all GAIN LEDs switched off With BIAS GND the configuration reproduces the input offset voltage at the output of the instrument This voltage may be measured with READ 3 The configuration m 0 is volatile and is reset to m 1 upon power on GAIN Example 2 Input INPT z Set query the preamplifier input conn...

Страница 45: ...rection of the signal at the SIM918 rear panel Ref Clock Sync connector to z IN 0 OUT 1 The direction is reset to IN upon power on SYNC 1 Example Reference Clock Frequency FREQ Query the reference clock frequency of the preamplifier in hertz The nominal frequency of the internal reference clock is 1 0 Hz The command can also be used to measure the frequency of an external reference clock If autoze...

Страница 46: ...uring that no digital clock transitions occur One consequence of APLL OFF is that the oscillator will require up to 250 s to reestablish the lock to an external reference when returning to CHOP ON Conversely with APLL ON the internal oscillator will continue to track an external 1 pps reference clock during CHOP OFF periods In this case there is no re lock time needed when returning to CHOP ON The...

Страница 47: ...s for the command to execute while internal switches are configured and the voltages are sampled and averaged Autozero is ON while READ executes and the reference clock is used during the measurement The results of READ will be unpredictable if the reference clock is external and Unlocked Remote commands are not processed until READ is complete READ 1 Example 12 Offset Trim OFST m j Set query offs...

Страница 48: ...s 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 STATUS signal STB Example 16 Service Request Enable SRE i j Set query the Service Request Enable register Bit i to j SRE 0 1 Example Standard Event Status ESR i Query the Standard Event Status Register Bit i Upon execution of ESR the returned bit s of the ESR regist...

Страница 49: ...erload Status Register Bit i Upon executing an OLSR query the returned bit s of the OLSR reg ister are cleared OLSR Example 3 Overload Status Enable OLSE i j Set query the Overload Status Enable register Bit i to j OLSE 4 Example Reference Clock Status RCSR i Query the Reference Clock Status Register Bit i Upon executing an RCSR query the returned bit s of the RCSR reg ister are cleared RCSR Examp...

Страница 50: ...sync 5 INPUT Open 6 INPUT Shield 7 BIAS GND 8 BIAS Shield 9 Both GAIN and GAIN autocalibrate 10 A button held upon power on reset The value 0 is returned if no button was pressed since the last LBTN A query of LBTN always clears the button code so a subse quent LBTN will return 0 LBTN Example 5 Overload OVLD Query the current overload condition The response is OVLD Overloaded 1 Bias 2 Output 4 Bia...

Страница 51: ...ne correspondence between the response of RCLK and bits in RCSR Once cleared by RCSR or CLS the reference clock status bits will stay cleared even though the reference clock state may persist and remain reported by RCLK RCLK Example UNLOCKED 3 4 8 Interface commands The Interface commands provide control over the interface between the SIM918 and the host computer Reset RST Reset the SIM918 to its ...

Страница 52: ... n005432 ver2 1 Self Test TST There is no internal self test in the SIM918 after the power on so this query always returns 0 TST Example 0 Operation Complete OPC Sets the OPC flag in the ESR register The query form OPC writes a 1 into the output queue when com plete but does not affect the ESR register OPC Example 1 Console Mode CONS z Set query the console mode to z OFF 0 ON 1 CONS causes each ch...

Страница 53: ...ific queries of 0 7 The second read of LEXE returns 0 Command Error LCME Query the Last Command Error code A query of LCME always clears the error code so a subsequent LCME will return 0 Valid codes are Value Definition 0 No command error since last LCME 1 Illegal command 2 Undefined command 3 Illegal query 4 Illegal set 5 Missing parameter s 6 Extra parameter s 7 Null parameter s 8 Parameter buff...

Страница 54: ...eger value Thus the only possible responses to the TOKN query are ON and 0 TOKN OFF Example Response Termination TERM z Set query the htermi sequence to z NONE 0 CR 1 LF 2 CRLF 3 or LFCR 4 The htermi sequence is appended to all query responses sent by the module and is constructed of ASCII character s 13 carriage return and 10 line feed The token mnemonic gives the sequence of characters A reset d...

Страница 55: ...3 4 Commands 3 23 Parity PARI z Set query the parity to z NONE 0 ODD 1 EVEN 2 MARK 3 SPACE 4 The value in boldface is the power on value TOKN ON PARI Example EVEN SIM918 Precision Current Preamplifier ...

Страница 56: ...ndef undef Bias Output OLSR OLSE Overload Status STATUS X X X X 3 2 1 0 X X X X 3 2 1 0 Leave Arrive Lock undef undef undef undef Unlock RCSR RCSE Reference Clock Status Figure 3 1 Status register model for the SIM918 Precision Cur rent Preamplifier There are two categories of registers in the SIM918 status model Event Registers These read only registers record the occurrence of defined events If ...

Страница 57: ...ates that the input buffer is empty and the command parser is idle Can be used to help synchronize SIM918 query responses ESB Event Status Bit Indicates whether one or more of the enabled events in the Standard Event Status Register is true MSS Master Summary Status Indicates whether one or more of the enabled status messages in the Status Byte register is true CESB Communication Error Summary Bit...

Страница 58: ...xecution Error Indicates the error in a command that was successfully parsed Out of range parameters are an example CME Command Error Indicates a command parser detected error URQ User Request Indicates that a front panel button was pressed PON Power On Indicates that an off to on transition has occurred 3 5 4 Standard Event Status Enable ESE The ESE acts as a bitwise AND with the ESR register to ...

Страница 59: ... input buffer to be flushed and resets the command parser RTSH RTS Holdoff Event Unused in the SIM918 CTSH CTS Holdoff Event Unused in the SIM918 DCAS Device Clear Indicates that the SIM918 received the Device Clear signal an RS 232 hbreaki Clears the input buffer and the output queue and resets the command parser 3 5 6 Communication Error Status Enable CESE The CESE acts as a bitwise AND with the...

Страница 60: ...of the overload 3 5 8 Overload Status Enable OLSE The OLSE acts as a bitwise AND with the OLSR register to produce the single bit OLSB message in the Status Byte Register SB The register can be set and queried with the OLSE command At power on this register is cleared 3 5 9 Reference Clock Status RCSR The Reference Clock Status Register consists of 4 event flags each of the flags is set by the cor...

Страница 61: ...ocked to locked Reading this register with the RCSR query clears all event bits that are set If the clock state persists e g the clock remains un locked the bits will remain cleared until the state ceases and reoc curs Use RCLK to query the current state of the reference clock 3 5 10 Reference Clock Status Enable RCSE The RCSE acts as a bitwise AND with the RCSR register to produce the single bit ...

Страница 62: ...3 30 Remote Operation SIM918 Precision Current Preamplifier ...

Страница 63: ...4 Circuit Description In This Chapter 4 1 Schematic Diagrams 4 2 4 1 ...

Страница 64: ...4 2 Circuit Description 4 1 Schematic Diagrams Circuit schematic diagrams follow this page SIM918 Precision Current Preamplifier ...

Страница 65: ... 3 6 3 12 3 19 shield button see Button BIAS Shield LED see LED BIAS Shield voltage iii 1 2 4 1 7 8 2 4 5 3 15 limits viii ix 1 7 2 4 5 voltage buffer 1 7 2 4 offset voltage 1 7 2 4 Block diagram 1 4 BNC iii viii ix 1 3 1 7 8 2 3 4 2 7 3 12 3 15 Buffer bias see Bias voltage buffer input 3 6 3 25 27 overflow 3 6 7 3 27 output see Output queue voltage see Output voltage buffer Button 1 9 3 18 3 26 A...

Страница 66: ...also Shield pro gram voltage current iii 1 2 1 4 6 1 8 2 2 impedance viii 1 2 2 2 LED see LED INPUT Open maximum cable length 2 3 offset voltage iii viii 1 2 1 6 7 2 5 2 8 3 12 3 15 adjusting see Trim input offset drift 2 8 measuring 3 12 3 15 zeroing 3 14 program see Shield program voltage resistance see Input impedance selecting viii 1 3 1 6 1 9 3 6 3 12 3 19 shield button see Button INPUT Shiel...

Страница 67: ... 6 7 3 6 7 3 11 14 3 18 3 20 3 22 3 25 29 Power line frequency see FPLC Preparation for use iv Program see Shield program voltage Query command 3 7 3 21 3 25 Quiescent operation 1 3 2 6 2 8 3 14 Rear panel 1 5 1 8 Reference clock viii 1 2 3 1 5 1 8 3 14 15 3 19 3 21 capture time 1 6 2 6 3 14 capture range see input frequency limits connector iii viii 1 2 1 6 1 8 2 4 2 6 7 3 13 3 28 direction 1 8 2...

Страница 68: ...y Status 3 15 3 24 registers 3 16 3 24 CESE 3 17 3 27 CESR 3 6 3 16 3 25 27 ESE 3 16 3 20 3 26 ESR 3 6 3 16 3 20 3 25 OLSE 3 17 3 20 3 28 OLSR 3 17 18 3 25 3 27 28 RCSE 3 17 3 29 RCSR 3 17 3 19 3 25 3 28 29 SB 3 16 3 25 29 SRE 3 16 3 20 3 25 Sticky bits 3 24 25 Temperature ix 2 6 Token 3 7 8 3 21 mode 3 19 3 22 Transimpedance iii 1 2 2 2 amplifier 1 2 2 2 3 Transimpedance stage iii 1 4 1 7 2 2 5 3...

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