SEMICONDUCTOR MODULATORS FOR USE IN SENSITIVE D. C. AMPLIFIERS
Date
1961-10
Authors
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Volume Title
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ORCID
Type
Degree Level
Masters
Abstract
It is generally found that when semiconductor diodes or transistors are used as modulators, small spurious signals are produced due to drift of leakage current and terminal voltage with temperature. Either or both of these can limit the sensitivity of any low level d. c. measuring instrument utilizing such a modulator.
A photo-sensitive semiconductor modulator with improved stability has been developed. It exhibits no leakage current drift due to the fact that reverse biases are avoided. The voltage drift has been reduced by a balancing technique which utilizes the symmetrical property of a commercially available silicon photo-diode pair. This modulator has demonstrated a stability of 2 x 10 -12amps./°0, which is at least two orders better than that obtainable by other techniques employing unmatched diodes or transistors.
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Citation
Degree
Master of Science (M.Sc.)
Department
Electrical Engineering