Engineering topics
Publications and source records attributed to Arentz, R. F..
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In the case of modern infrared focal planes, one of the major problems is related to the noise contribution of the cooled, impedance-matching device used as the preamplifier stage in the detector electronics system. An ideal preamp device should have the low-noise advantages of a buried-channel device and operate isothermally with the low-temperature detector array. The Ge JFET might provide this ideal device. A testing program with Ge JFETs is discussed. It is concluded that germanium JFETs offer an attractive alternative for cryogenic preamplifier designs. They operate well with high transconductance and low noise at LHe temperatures. It is believed that these devices point the way for the development of large, integrated-array, long wavelength, infrared focal planes which incorporate germanium detectors, germanium load resistors, and germanium preamplifiers within the same monolithic structure.
It is pointed out that the simple and traditional method of measuring resistance using an electrometer is ineffective since it is limited to a narrow and nonrepresentative range of terminal voltages. The present investigation is concerned with a resistor measurement technique which was developed to select and calibrate the Transimpedance Mode Amplifier (TIA) load resistors on the Infrared Astronomical Satellite (IRAS) for the wide variety of time and voltage varying signals which will be processed during the flight. The developed method has great versatility and power, and makes it possible to measure the varied and complex responses of nonideal feedback resistors to IR photo-detector currents. When employed with a stable input coupling capacitor, and a narrow band RMS voltmeter, the five input waveforms thouroughly test and calibrate all the features of interest in a load resistor and its associated TIA circuitry.