SRS
SIM918 – Current preamplifier
Overview
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.
Feature
• 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
Technical Specifications
Input offset voltage: <10 ?V (autozero enabled)
Input impedance: <1? (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): ?2 %
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 M?
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 G? (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
Others
N/A
