Automatic-tuning circuit for integrated continuous-time MOSFET-C filters
US5994951A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 20, 1998 |
| Grant date | Nov 30, 1999 |
| Priority date | — |
| Expiry date | Jan 20, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/04
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An integrated, tuning circuit for tuning a MOSFET-C filter contains a tuning MOSFET and a differential amplifier. A current source is connected to the drain of the tuning MOSFET. The output of the amplifier is coupled to the drain of the tuning MOSFET and to a terminal that connects to the drains of the MOSFETs of the filter, so that the equivalent resistance of the filter is dependant on the current. The current source is coupled to a reference current generator, such that current supplied by the current source to the tuning MOSFET is proportional to the current supplied in the reference current generator, which in turn varies with process and environmental conditions of a capacitance. As a result, changes in process and environmental conditions oppositely affect the capacitance and resistance in the filter, resulting in a fixed RC product and fixed frequency response from the filter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.