Stanford Research SIM911 – BJT Preamplifier

The Stanford Research SIM911 is a low-noise BJT preamplifier designed to amplify weak analog signals from DC to 1 MHz with exceptional input noise performance and programmable gain settings from 1 to 100. Optimized for integration within the SIM900 Mainframe ecosystem, the module operates independently with appropriate DC power and delivers stable, accurate amplification across configurable input modes and coupling options.

Technical Specifications

• Frequency Range: DC to 1 MHz (gain-independent bandwidth); -3 dB at 1.9 MHz typical


• Input Noise: 1.8 nV/√Hz @ 1 kHz (Gain ≥ 10); 12 nV/√Hz @ 1 kHz (Gain = 1)


• Input Current Noise: ~1.2 pA/√Hz


• Input Impedance: 100 kΩ in parallel with ~35 pF


• Programmable Gain: 1 to 100 (1-2-5 sequence)


• Gain Accuracy: ±0.5% (DC to 100 kHz); ±5% @ 1 MHz typical


• Gain Stability: 200 ppm/°C


• CMRR: 85 dB


• AC Coupling Option: 0.7 Hz -3 dB frequency


• Power Requirements: +5 V (50 mA typical, 100 mA max); ±15 V (50 mA typical, 300 mA max)

Key Features

• Configurable differential (A-B), single-ended (A), or internally grounded input modes


• DC or AC coupling selectable; BNC shield floating or grounded option


• Dual parallel outputs (front and rear panel); rear and front outputs share a common connection


• Clock-stopping microcontroller architecture eliminates digital noise contamination


• Remote serial interface control with front panel button adjustment capability


• Overload indication status signal

Typical Applications

• Precision measurement of low-amplitude analog signals


• Lock-in detection and signal recovery


• Sensor front-end amplification


• Transducer signal conditioning

Compatibility & Integration Single-wide SIM module format with BNC connectors. Operates standalone or integrated within SIM900 Mainframe systems. Output drive capability: one 50 Ω load while the parallel output connects to high impedance loads.