Tuning filters having transconductor cells
US7135915B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 13, 2004 |
| Grant date | Nov 14, 2006 |
| Priority date | — |
| Expiry date | Jan 13, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/1291
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
In one embodiment, a filter with a main signal path having one or more biquadratic filter sections is tuned using a tuning circuit based on a biquadratic filter that can be configured to oscillate at the filter's cutoff frequency. In one application, a tuning circuit outside of the main signal path is used to tune each biquadratic filter section of the main signal path. In another application, each filter section along the main signal path has a biquadratic filter that can oscillate and corresponding tuning elements that enable the filter section to tune itself. According to certain embodiments of the present invention, a biquadratic filter is made to oscillate by applying a common-mode voltage signal to the inputs of the filter's third transconductor cell to make the cell's transconductance go to zero. The invention may also be implemented in the context of filters having ladder structures in their main signal path.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.