The Stanford Research Systems SR552 is a low-noise voltage preamplifier that amplifies weak signals directly at the measurement source, minimizing cable noise and improving lock-in amplifier sensitivity. Built with a BJT input stage, it delivers input noise as low as 1.4 nV/√Hz at 1 kHz and supports both single-ended and differential input configurations. The unit integrates with SRS lock-in amplifiers via 9-pin control cable or operates independently with external ±20 VDC / +5 VDC power supplies.
Technical Specifications
Input Stage
• Input impedance: 100 kΩ || 25 pF
• Input noise density: 1.4 nV/√Hz (1 kHz), 1.6 nV/√Hz (100 Hz), 2.5 nV/√Hz (10 Hz)
• Maximum input voltage (overload): 70 mV RMS
• Input damage threshold: 50 V DC / 20 V AC
• Input coupling: AC coupled, 0.016 Hz lower limit
• Selectable input: Single-ended or Differential
Gain & Performance
• Gain settings: 10, 20, 50, or 100 (fixed at 100 with DSP lock-ins; automatic with SR510/SR530)
• Gain accuracy: ±2% (2 Hz to 100 kHz)
• Gain stability: 200 ppm/°C
• Full-scale input sensitivity: 10 nV to 200 mV
• Common mode rejection ratio: 100 dB at 100 Hz (1 V input)
• Maximum output voltage: 10 Vpp
Frequency Response
• Bandwidth: 1 Hz to 100 kHz (AC coupled effective from 0.016 Hz)
• Gain accuracy range: 2 Hz to 100 kHz
Power & Connectors
• Power source: SRS lock-in amplifier via 9-pin cable (SR510, SR530, SR810, SR830, SR850, SR124) or external +20 VDC (100 mA), +5 VDC (10 mA), −20 VDC (100 mA)
• Output A: Signal output, 600 Ω single-ended
• Output B: Shielded ground
– Key Features
• BJT input design for low input noise and moderate input impedance
• AC coupling with extended low-frequency response to 0.016 Hz
• Switch-selectable single-ended or differential inputs
• High common-mode rejection (100 dB at 100 Hz)
• Gain auto-calibration with legacy SRS models; fixed gain with DSP variants
– Typical Applications
Lock-in measurement systems in optics, materials characterization, and electronics requiring sensitivity enhancement and noise reduction at the signal source.
– Compatibility & Integration
Works with SR510, SR530, SR810, SR830, SR850, and SR124 lock-in amplifiers. DSP models require manual gain compensation (divide measurements by 100).
