Method and apparatus for tuning an active filter
US7477098B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 8, 2007 |
| Grant date | Jan 13, 2009 |
| Priority date | — |
| Expiry date | Feb 24, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H2210/043
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A tuning circuit for tuning an active filter includes a resistor-capacitor circuit comprising a variable capacitor and a resistor equivalent to a first resistor and a second resistor serially connected to the first resistor, a voltage generator for providing a constant reference voltage to the first resistor, a current replicating unit for replicating a current based on the constant reference voltage, a comparator for comparing a charging voltage as the current is charging a variable capacitor with the constant reference voltage, a counter for counting a number of cycles of a clock signal until the charging voltage reaches the constant reference voltage, a adjustment unit for calibrating a capacitance of the variable capacitor based on the number of cycles of a clock signal and a target count value associated with a predetermined RC time constant.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.