AN INTEGRATING PREAMPLIFIER FOR INDIUM ANTIMONIDE INFRARED DETECTORS

A circuit for InSb detectors, the most popular 1-5 micron detector in astronomical applications, is presented in which the feedback resistor is replaced by an integrating capacitor. The circuit is free from disadvantages associated with a large feedback resistor, such as saturation and the time constant that causes a reduction in the signal under conditions of rapid sampling. The main advantage of the new circuit is its versatility: it has a wide dynamic range, the sample rate may be selected from a range of four orders of magnitude, precision measurement of incident radiation and precision timing of events are possible, it has a fast spectrum-scanning mode, and may be operated in a purely dc mode.