SRS SIM911 BJT Voltage Preamplifier 1.8 nV/√Hz input noise, input impedance 100 kΩ // 35 pF

• 1.8 nV/√Hz input noise
• Low output noise
• 1 MHz bandwidth
• Selectable gain from 1 to 100
• AC or DC coupled
• Differential or single-ended input
• 85 dB CMRR
• Remote interface

The unit maintain very low output noise resulting in exceptional overall noise performance-even at low gain levels. The bandwidth of this preamplifier is independent of gain setting so waveforms do not change shape as the gain is varied. Dual parallel outputs (one frontand one rear) provide flexibility in cabling.

Inputs can be configured as differential (A-B), single-ended (A), or internally grounded, and can be either AC or DC coupled. Additionally, the BNC input shields can be floated, avoiding spurious ground loops when measuring remote signals.

The digital control circuitry in the SIM911 is designed with a special clock-stopping architecture in which the microcontroller is turned on only when settings are being changed. 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 an overload condition. The SIM911 can be operated outside the SIM mainframe by powering it with the required DC voltage.