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SIM Series SIM918 ... from $1395
SIM918 Precision current preamplifier
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SIM918 Precision Current Preamplifier
  • Input offset voltage <10 µV
  • DC bias current <2 pA
  • Current gain of 106 to 108 V/A
  • 15 fA/√ Hz input noise (108 V/A)
  • Autozero feature
  • Bias voltage input
The SIM918 Current Preamplifier is ideal in applications in which the input offset voltage must be kept to a minimum. The DC voltage difference between the two inputs (current input and voltage bias) is accurately measured every 2 seconds, and is nulled. The result is a current amplifier with less than 10 µV input offset voltage. This autozeroing feature can be engaged or inhibited remotely or from the front panel, giving you flexibility in sensitive applications.
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SIM918 Precision Current Preamplifier

The SIM918 Current Preamplifier is ideal in applications in which the input offset voltage must be kept to a minimum. The DC voltage difference between the two inputs (current input and voltage bias) is accurately measured every 2 seconds, and is nulled. The result is a current amplifier with less than 10 µV input offset voltage. This autozeroing feature can be engaged or inhibited remotely or from the front panel, giving you flexibility in sensitive applications.

As a current amplifier, the SIM918 offers input noise as low as 15 fA/√Hz and adjustable current gain (106 to 108 V/A). The output voltage range is ±10 V for all gain settings. Input bias current is less than 2 pA (DC), and the instrument has up to 22 kHz of (gain-dependent) bandwidth.

There is a voltage bias input for setting the virtual ground potential to an external DC source. This input can range over ±5 V. The bias voltage can be internally grounded.

An autozero sync input/output connection is also provided. In the internal autozeroing mode, this port provides a one pulse-per-second (pps) output synchronous with the internal switching circuitry. In the external mode, a 0.9 to 1.1 pps input signal generates the reference for synchronizing the circuitry.

The SIM918 provides maximum flexibility for cabling and grounding. The shield of the current input BNC can be switched between chassis 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 the input cable, while the excited current flows through the center conductor to the SIM918. The shield of the voltage bias BNC can be independently grounded or floated.

The digital control circuitry in the SIM918 is designed with SRS's special clock-stopping architecture in which the microcontroller is turned on only when settings are being changed (note that the autozeroing circuitry is independent of the microcontroller, and can operate while the digital clock is stopped). This guarantees that no digital noise can contaminate low-level analog signals. Settings may be changed from the front panel or through the remote interface. All instrument settings can also be queried via the remote interface. The module generates a status signal to alert the user of any overload conditions.

 

 

 

 

 

Phone: (408)744-9040 • Fax: (408)744-9049 • email: info@thinkSRS.comwww.thinkSRS.com

SIM918 Precision Current Preamplifier
Specifications
Input offset voltage <10 µV (autozero enabled)
Input impedance <1Ω (DC), 18 pF
Current gain 106 V/A, 107 V/A or 108 V/A
Gain accuracy
     (106 V/A) ±0.1 %
     (107 V/A) ±0.1 %
     (108 V/A) ±1 %
Gain stability
     (106 V/A) ±10 ppm/°C
     (107 V/A) ±50 ppm/°C
     (108 V/A) ±100 ppm/°C
Bandwidth (typ.)
     (106 V/A) 22 kHz
     (107 V/A) 12 kHz
     (108 V/A) 4 kHz
Input noise (typ.)
     (106 V/A) 130 fA/√Hz @ 100 Hz
     (107 V/A) 42 fA/√Hz @ 100 Hz
     (108 V/A) 15 fA/√Hz @ 100 Hz
AC bias current 3.5 pA rms (w/ autozero engaged)
DC bias current <2 pA
Input BNC shield Can be tied to chassis ground, set to the rear-panel analog input (Prog), or driven from the bias input
Bias Input
Range ±5 VDC
Frequency response 0.2 Hz
Input impedance 10 MΩ
Input BNC shield Ground or float
Program Input (rear panel)
Function Connects to current input BNC shield when selected
Range ±60 V
Input impedance 3 GΩ (typ.)
Output
Range ±10 V
Max. current 100 mA
Autozero
Function select On or Hold
Int. switching freq. 0.5 Hz
Ext. sync in/out 1 pulse per second (pps), TTL level. Functions as a 1 pps sync output in internal mode.
Sync capture range ±10 % of 1 pps
General
Operating temperature 0 °C to 40 °C, non-condensing
Interface Serial via SIM interface
Connectors BNC (3 front, 2 rear)
DB15 (male) SIM interface
Power Power supplied by the SIM900 Mainframe, or optionally by a user-supplied DC power supply (±15 V and +5 V)
Dimensions 1.5" × 3.6" × 7.0" (WHL)
Weight 1.7 lbs.
Warranty One year parts and labor on defects in materials and workmanship
 
 
 
 
Phone: (408)744-9040 • Fax: (408)744-9049 • email: info@thinkSRS.comwww.thinkSRS.com