Closed loop amplitude demodulator
US4403194A · kind A · utility
Inventor
Key dates
| Filing date | Mar 11, 1981 |
| Grant date | Sep 6, 1983 |
| Priority date | — |
| Expiry date | Mar 11, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D1/06
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An improved substantially "zero distortion" four quadrant modulator of the type including a pair of differential elements respectively coupled to the Y input port terminals of the modulator and exhibiting nonlinear amplitude transfer functions, includes the means for substantially linearizing the nonlinear transfer function. The means includes a pair of operational amplifiers, each having an input coupled to a respective terminal of the Y input port and an output coupled to the corresponding differential element so that the differential element is disposed in the feedback path of the operational amplifier. An improved demodulator is provided by detecting the amplitude modulated signal with a first detector and applying the detected signal to one input of a signal comparator. A feedback loop couples the output of the signal comparator to its other input. In particular the output is coupled to the Y input port of a substantially zero distortion modulator, which has the X input adapted to receive a continuous wave signal. The output of the modulator is detected by a second detector which in turn is coupled to the other input of the signal comparator. The first and second detectors are…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.