Programmable/tunable active RC filter
US7193455B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 24, 2004 |
| Grant date | Mar 20, 2007 |
| Priority date | — |
| Expiry date | Aug 24, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/04
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A programmable/tunable active low-pass filter at least has the resistors, capacitors and shunt control devices. It uses the linear property of the MOSFET to implement the shunt control devices. Based on the first-ordered linear analysis of the transfer function of the active-RC filter, it is found that the cut-off frequency of the active-RC filter can be tuned via the effective small-signal current controlled by the shunt control devices. Therefore, the filter of the present invention allowed users for fine tune the cut-off frequency linearly through the shunt control devices when the variation of the environment or procedure parameters of manufacture (i.e. thermo-effects) cause the cut-off frequency drift, thus, the cut-off frequency can be kept in a constant value. In addition, it needs the different cut-off frequency from the different application. The present invention also provides a device for programming the cut-off frequency to a desired frequency value dependent upon the conditions of application within a big range. Thus, the same filter circuit can be used in many purposes widely.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.