Stanford Research SR554 Transformer Preamplifier

The Stanford Research Systems SR554 Transformer Preamplifier delivers ultra-low-noise amplification for precision measurement applications requiring exceptional common-mode rejection and gain stability. Built around a transformer-coupled input architecture, the SR554 provides galvanic isolation exceeding 40 dB from DC to 500 MHz while operating across source impedances of 0.05 Ω to 1 kΩ. Two operational modes accommodate different measurement demands: bypassed mode supplies 100× gain through the passive transformer alone, while non-bypassed mode adds a buffer amplifier to achieve 500× gain with low output impedance.

– Technical Specifications

• Input noise: 0.1 nV/√Hz
• Bandwidth: 0.1 Hz to 40 kHz
• Gain: 100× (bypassed); 500× (non-bypassed)
• Gain accuracy: 5% (fixed source resistance)
• Gain stability: 100 ppm/°C
• Common-mode rejection ratio: >120 dB below 1 kHz, 140 dB @ 100 Hz, up to 160 dB below 10 Hz
• Common-mode range: Primary floats to ±100 VDC
• Input impedance: 0.5 Ω (transformer + buffer); >5 kΩ (transformer only)
• Maximum input: 14.0 mV RMS transformer+buffer; 350 mV RMS transformer only
• Maximum output: 100 Vpp transformer only; 20 Vpp transformer+buffer

– Key Features

• Transformer isolation provides DC blocking and EMI rejection across wide frequency span
• Selectable gain configurations optimize for signal conditioning or direct buffering
• Floating primary accommodates high common-mode voltages
• Differential and single-ended input/output connectivity
• Compact form factor: 3.75″ × 3.0″ × 7.5″ (W × H × L); 4 lbs

– Typical Applications

Low-temperature synchronous detection, high-impedance source conditioning, common-mode noise rejection in differential measurements, isolated signal pre-amplification for lock-in detection systems.

– Compatibility & Integration

Operates as a front-end instrument for SRS lock-in amplifiers (SR510, SR530, SR810, SR830, SR850, SR124) via control cable, or standalone with external ±20 VDC supply (100 mA).