Method and apparatus for tuning filters
US6259311A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 23, 1998 |
| Grant date | Jul 10, 2001 |
| Priority date | — |
| Expiry date | Dec 23, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/245
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A highly accurate tuning circuit for a tunable filter is provided which trims an RC time constant based on variances in both a formed capacitive component as well as variances in formed resistive components. A capacitor and resistor based tuning control circuit includes both a formed capacitor based tuning reference current generator and a formed resistor based tuning voltage reference generator. Each generates a voltage reference which is compared to the other to determine control signals for tuning a tunable resistive component forming the resistive portion of the RC time constant of the relevant filter. The resistive component is tuned by shorting selective resistors in the tunable resistive component. By tuning the RC time constant to the particular variances in capacitor and resistor components formed in the integrated circuit, the RC time constant of the tunable filter can be tuned to a desired absolute value within a tighter tolerance range than was previously available with conventional tuning circuits which provided tuning control based only on the variances of formed resistor elements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.