Integrated tunable filter for broadband tuner
US6915121B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 6, 2002 |
| Grant date | Jul 5, 2005 |
| Priority date | — |
| Expiry date | Jan 10, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03J3/28
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A tunable filter circuit includes a first differential pair biased by a first current, a second differential pair biased by a second current, a first capacitor and a second capacitor. The tunable filter circuit of the present invention can be configured as a bandpass filter or a bandstop filter by connecting the input voltage signal to different input nodes of the tunable filter circuit. The tunable filter circuit can be tuned by adjusting the values of the first current and the second current. In an alternate embodiment, frequency tuning is achieved either by switching capacitive loads or changing resistive impedances introduced at the emitter of the differential pairs, which also extends the input voltage range of the filter. This emitter resistance is implemented using MOS switches whose on-resistance can be controlled for a precise tuning within a large frequency range.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.