Dual-stage filter with feedback
US4563652A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 12, 1985 |
| Grant date | Jan 7, 1986 |
| Priority date | — |
| Expiry date | Apr 12, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/04
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A dual-stage band pass-band reject filter with feedback. Two state variable band pass filters with identical topology are cascaded as first and second stages. Each stage employs two inverting adders and two inverting integrators in a state variable topology, and each provides a band pass output and a band reject output. Both stages are selectively tuned to the same fundamental frequency. The filter output may be switched from a band pass to a band reject mode. In the band reject mode decreased attenuation of harmonics of the fundamental frequency is achieved by providing a predetermined amount of feedback from either the band reject output or band pass output of the second stage to the input of a respective one of the two adders of the first stage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.