The SIM965 is a continuous-time, digitally-programmable analog filter module for the SRS SIM900 Mainframe that delivers precise signal conditioning through Bessel and Butterworth filter topologies. Operating from 1 Hz to 500 kHz with selectable rolloff rates (12, 24, 36, or 48 dB/octave), it supports both high-pass and low-pass configurations with 3-digit cutoff frequency resolution. Unity gain design and high input impedance (1 MΩ) minimize signal loading. AC or DC coupling options accommodate diverse analog front-end requirements. The module employs clock-stopping architecture to prevent digital noise contamination—critical for sensitive measurements. Output noise remains below 200 µVrms across a 1 MHz bandwidth, with THD of 0.01% at 1 kHz. Maximum input voltage ranges from ±5 V to ±10 V depending on filter settings.
Technical Specifications
• Filter Types: Bessel, Butterworth
• Frequency Range: 1 Hz to 500 kHz
• Cutoff Frequency Resolution: 3-digit
• Operation Modes: High-pass, Low-pass
• Rolloff Rates: 12 dB/octave, 24 dB/octave, 36 dB/octave, 48 dB/octave
• Gain: 1× (unity)
• Input Impedance: 1 MΩ
• Coupling: AC or DC
• Bandwidth: Greater than 1 MHz
• Output Noise: < 200 µVrms (1 MHz bandwidth)
• THD: 0.01% at 1 kHz
• Maximum Input Voltage: ±5 V (48 dB/octave Butterworth), ±7 V (36 dB/octave Butterworth), ±10 V (all other settings)
– Key Features
• Continuous-time analog filtering—no sampling artifacts
• Programmable via serial interface through SIM900 Mainframe
• Low harmonic distortion and low noise floor for precision analog work
• Dual filter topologies enable phase-response and magnitude-response optimization
• Multiple rolloff selections support steep attenuation when needed
• Single-wide module format for SIM900 integration
– Typical Applications
• Sensitive analog signal conditioning in research and laboratory environments
• Anti-aliasing filtering before analog-to-digital conversion
• Noise rejection in low-level measurement circuits
• Multi-channel filter banks via SIM900 cascading
– Compatibility & Integration
The SIM965 installs directly into the SRS SIM900 Mainframe and integrates with RS-232 and GPIB control interfaces. Unlimited cascading of SIM900 Mainframes supports multi-channel configurations. Optional pairing with the SIM910 JFET Preamplifier or SIM911 BJT Preamplifier provides signal amplification when required.
