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US 4,873,492 AGranted
Amplifier with modulated resistor gain control
AssigneeAmerican Telephone and Telegraph Company, AT&T Bell Laboratories
InventorRobert E. Myer
Life of this patent
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AssigneeAmerican Telephone and Telegraph Company, AT&T Bell Laboratories
InventorRobert E. Myer
Estimating the term…
An automatic gain control circuit for an amplifier operating over a prescribed frequency range detects the output level of the amplifier; and couples a repeated predetermined waveform occurring at a rate greater than the reciprocal of twice the upper frequency of the prescribed frequency range to the output level signal. The waveform varying level signal is compared to a reference threshold to control the gain of the amplifier through a switched resistive elemement in the amplifier feedback path. The repeated waveform variations about the amplifier output level causes the value of the switched resistance to vary as a function of the output level. A low pass filter connected to the amplifier output removes switching transients resulting from the high frequency changes in the switched resistive element. The gains of a plurality of amplifiers may be determined by a common control for accurate tracking over a wide dynamic range.
A circuit for controlling the gain of an amplifier operating over a prescribed frequency range having an input and an output comprising:
In a system having a plurality of amplifiers operating over a prescribed frequency range each having an input and an output, a common circuit for controlling the gains of the amplifiers comprising:
A signal amplifying circuit comprising:
Dependencies are inferred from the claim text.