High temperature superconductor transimpedance amplifiers using serially connected bi-crystal junction SQUID arrays

This article discusses the design and measurement of high temperature superconductor transimpedance amplifiers using bi-crystal junction SQUID arrays. The peak to peak modulation voltages of the arrays as a function of their SQUID inductance were measured. The measured transresistance, dV/sub o//dI/sub i/, of a 30-element array of 5-pH SQUIDs was 4 V/A. The voltage modulation depth of the 30-element array was 2 mV and the white noise of the array was 1.0 nV/Hz/sup 1/2/ at 100 kHz. The dynamic range of the array was 120 dB in a one hertz bandwidth. This device has the potential to be used as a broadband amplifier for low impedance sources.