Stanford Research SIM918 – Precision Current Preamplifier

The Stanford Research SIM918 is a precision current preamplifier module engineered to convert minute input currents into proportional voltage outputs with exceptional fidelity. Part of the Small Instrumentation Modules (SIM) family, it delivers input offset voltages below 10 µV through active autozeroing—a feature that automatically nulls offset drift every 2 seconds. The module achieves current noise as low as 15 fA/√Hz at maximum gain, making it ideal for applications demanding femtoampere-level sensitivity.

– Technical Specifications

• Input Stage: <1 Ω DC input impedance with 18 pF capacitance; DC bias current <2 pA; input offset voltage <10 µV (autozero enabled)
• Transimpedance Gain: Selectable 10^6 V/A, 10^7 V/A, or 10^8 V/A
• Output: ±10 V range across all gain settings
• Input Noise: 15 fA/√Hz at 10^8 V/A gain
• Bandwidth: Gain-dependent; up to 22 kHz and 10 kHz
• Bias Input: ±5 V range; sets virtual ground to external DC source or internal ground
• Program Input (rear panel): ±60 V range, 3 GΩ input impedance; connects to current input BNC shield when selected
• Operating Temperature: 0 °C to 40 °C, non-condensing

– Key Features

• Autozeroing eliminates input offset drift with remote or front-panel control
• Autozero sync input/output: accepts 0.9 to 1.1 pps external signal or provides 1 pps internal reference
• Adjustable transimpedance gain accommodates diverse current ranges
• Unbuffered program input for external potential control

– Typical Applications

Suitable for scanning microscopy, low-temperature physics research, and detector readout systems requiring sub-picoampere current measurement.

– Compatibility & Integration

Designed for the SIM900 Mainframe, which provides power, clock synchronization, and communication. Modules operate standalone or within the SIM chassis ecosystem.