SR556 — Current preamplifier • 1 V/nA fixed gain • 5 fA/VHz input noise • Bias voltage input • Powered by SRS lock-in amplifiers The SR556 is a low-noise, high-bandwidth, fixed-gain current (trans-impedance) amplifier designed to work with SRS lock-in amplifiers. Current amplifiers provide gain close to the experimental detector, allowing the user to minimize input cable length and its corresponding input capacitance. The SR556 minimizes noise and pickup before they permanently degrade the signal-to-noise ratio, reducing measurement time in noise-limited experiments. Power is brought from the lock-in by a 9-pin cable. The SR556 can also be operated independently by applying the appropriate DC power. Gain Bandwidth Input noise (typ.) Current input Impedance Bias current DC bias input Range Settling time Impedance Gain accuracy Gain stability Output Power Mechanical Weight Warranty 109 V/A 3 kHz (-3 dB) 5 fA/VHz at 1 kHz <50 Q <3 pA ±5 VDC <250 ms 1 MQ 1 % ±50 ppm/°C 20 Vpp max. balanced differential 10 mA max., 50 Q Supplied by SR510, SR530, SR810, SR830, SR850 or SR124 via control cable 3.0" x 1.3" x 5.1" (WHD) 10 oz. One year parts and labor on defects in materials and workmanship Ordering information SRS Stanford Research Systems phone: (408)744-9040 www.thinkSRS.com