Amplifier with modulated resistor gain control
US4873492A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 5, 1988 |
| Grant date | Oct 10, 1989 |
| Priority date | — |
| Expiry date | Dec 5, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03G3/3026
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.