We present a cryogenic charge amplifier system developed for an InSb photodiode array for use in high-resolution infrared spectrometers. After a general introduction, the detailed circuit diagram of the charge integrator is presented. The integrator features a new optoelectronic method for resetting the integrating capacitor; the whole charge amplifier is placed in the cold Dewar to reduce microphonics and to increase noise immunity. The analysis of the expected performance is given along with the results of some preliminary tests performed on a two-channel version of the system. A single-channel version under current use in the TIRGO photometer shows noise figures in good agreement with our prediction; the measured noise is ~210 electrons in 1-s integration time, which corresponds to a NEP of 2.8 × 10-17 W/[equation] in the K band (2.2 µm).
© 1986 Optical Society of America
Don Hartill, Franco Lisi, and Andrea Bettarini, "An InSb charge amplifier for use in a spectrometer array," Appl. Opt. 25, 1701-1706 (1986)