Lock-In Preamplifier SR554 — Transformer preamplifier with differential input SR554 Transformer Preamplifier The SR554 is a low-noise, transformer-coupled preamplifier optimized for source impedances between 0.05 Ω and 1 kΩ. With an input noise of only 0.1 nV/√Hz, the SR554 can be used in a wide range of low-noise applications. It is the ideal preamplifier for low-temperature, synchronous detection applications where isolation between the experimental sample and the lock-in amplifier is critical. · Transformer-coupled input · 0.1 nV/√Hz input noise · 0.1 Hz to 40 kHz bandwidth · Gain of 100 or 500 · Single-ended and differential inputs · >40 dB isolation from DC to 500 MHz · Powered by SRS lock-in amplifiers The SR554 can operate in one of two modes. In the “bypassed” mode, the instrument is simply a passive transformer with a turns ratio of 100, providing an overall voltage gain of 100. In the “non-bypassed” mode, an additional amplifier (gain of 5) is added, increasing the overall gain to 500 and providing a low-impedance (<1 Ω) output. In the bypassed mode, the SR554 requires no external power. When using the output amplifier, ±20 VDC must be supplied. The preamplifier connector on SRS lock-ins can be used to power the SR554. Stanford Research Systems

SR554 Noise Figure Contours Mode Single-ended or differential Noise 0.1 nV/√Hz Source impedance 0.05 Ω to 1 kΩ (recommended) CMRR >120 dB below 1 kHz Common mode range Primary can float to ±100 VDC Gain 100× (transformer only) 500× (transformer and buffer) Max. freq. response 0.1 Hz to 40 kHz Isolation >40 dB, DC to 500 MHz Output Single-ended or differential Maximum output 100 Vpp (transformer only) 20 Vpp (transformer and buffer) Output impedance >5 kΩ (transformer only) <1 Ω (transformer and buffer) Power Supplied by SR510, SR530, SR810, SR830, SR850 or SR124 via control cable. External ±20...