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Programmable electronic synthesized capacitanceA predetermined and variable synthesized capacitance which may be incorporated into the resonant portion of an electronic oscillator for the purpose of tuning the oscillator comprises a programmable operational amplifier circuit. The operational amplifier circuit has its output connected to its inverting input, in a follower configuration, by a network which is low impedance at the operational frequency of the circuit. The output of the operational amplifier is also connected to the noninverting input by a capacitor. The noninverting input appears as a synthesized capacitance which may be varied with a variation in gain-bandwidth product of the operational amplifier circuit. The gain-bandwidth product may, in turn, be varied with a variation in input set current with a digital to analog converter whose output is varied with a command word. The output impedance of the circuit may also be varied by the output set current. This circuit may provide very small ranges in oscillator frequency with relatively large control voltages unaffected by noise.
Document ID
19870013462
Acquisition Source
Legacy CDMS
Document Type
Other - Patent
Authors
Kleinberg, Leonard L.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 13, 2013
Publication Date
February 17, 1987
Subject Category
Electronics And Electrical Engineering
Accession Number
87N22895
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Patent
NASA-CASE-GSC-12961-1|US-PATENT-4,644,306
Patent Application
US-PATENT-APPL-SN-754707
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