Low-noise wide-band amplification system for acquiring prebreakdown current pulses in liquid dielectrics

A low-noise wideband amplification system consisting of a preamplifier with input protection circuit and an amplifier were developed for measuring the prebreakdown currents in liquid dielectrics. The system design considerations and experimental results are presented. The preamplifier was voltage-sensitive with a voltage gain of 154 V/V, and had a bandwidth of 56 MHz and an equivalent noise voltage spectral density of 0.93 nV/Hz/sup 1/2/. The amplifier had a voltage gain of about 12 and a bandwidth of 58 MHz and was capable of driving mod 2 mod V across two paralleled 50 Omega loads. The overall system had a gain of 92400 V/A when loaded with 50 Omega , and it had a minimum detectable current of 1.9 mu A for an overall bandwidth of about 29 MHz. >