Multiplexing arrangement for a plurality of voltage controlled filters
US4368541A · kind A · utility
Inventor
Key dates
| Filing date | Jun 30, 1980 |
| Grant date | Jan 11, 1983 |
| Priority date | — |
| Expiry date | Jun 30, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03J5/0263
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A multiplexing arrangement enables a plurality of control voltages for controlling respective ones of a plurality of varactor controlled tunable filters, employed, e.g., prior to the tuner of a television receiver to reject undesired signals, to be generated by a single digital to analog (D/A) converter. A controller, which may, e.g., comprise a microcomputer, sequentially applies digital control words to the D/A converter and substantially synchronously causes the resultant control voltages generated by the D/A converter to be applied, through respective switches to the tunable filters. The control voltages are applied to capacitors connected to d.c. control lines for the tunable filters. The high impedance of the varactor diodes included in the filters enables the capacitors to store respective control voltages for relatively long intervals before the control voltages need to be refreshed. This enables a large number of tunable filters to be controlled by a single D/A converter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.