Mixer injection voltage compensation circuit
US4160213A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 29, 1977 |
| Grant date | Jul 3, 1979 |
| Priority date | — |
| Expiry date | Sep 29, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03B2201/0208
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
In a VHF tuner for a television receiver including a varactor controlled local oscillator (LO), a field effect transistor (FET), arranged as a mixer for generating an IF signal in response to RF and local oscillator signals, is biased with respect to the amplitude of the local oscillator signal corresponding to channel 6 to inhibit the development of intermodulation and cross-modulation products which tend to manifest themselves at channel 6 and to provide a suitably large conversion gain at channel 6. A varactor diode is coupled in serial fashion between the varactor controlled LO and the FET and is controlled in response to the tuning voltage, normally utilized to control the frequency of oscillation of the LO, to couple signals to the FET from the LO having approximately the same amplitude as the amplitude of the signal coupled to the FET from the LO at channel 6 throughout the low VHF band including channels 2-6 so as to substantially maintain the combination of desired mixer bias and mixer input signal throughout the low VHF band.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.