Switchable FET distortion generator
US5162748A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 29, 1991 |
| Grant date | Nov 10, 1992 |
| Priority date | — |
| Expiry date | Nov 29, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2200/72
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A communications system includes a transmission channel in which, for efficiency, a processor such as an amplifier is operated in a nonlinear mode. When the signal is modulated in a manner which is affected by the nonlinearity of the processor, such as a multicarrier modulation, a distortion linearizer is used. The distortion linearizer incluees the source-to-drain conductive channel of a FET. The gate of the FET is coupled to ground by an impedance which may be a low inductance, and the gate is biased relative to the channel, possibly near pinchoff, to cause the channel to exhibit desirable gain expansion and phase shifts in response to signal input level, which are selected to compensate the distortion of the nonlinear processor. When the signal is modulated in a manner which is not significantly affected by the nonlinearity of the processor, as for example frequency modulation, the distortion linearizer is switched to a linear or ON mode, in which the amplitude and phase are invariant with signal level. The switching is accomplished by adjusting the gate-to-channel voltage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.