Adjustable active filter
US4595885A · kind A · utility
7Cited by
9References
9Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 1, 1984 |
| Grant date | Jun 17, 1986 |
| Priority date | — |
| Expiry date | Oct 1, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/04
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An adjustable active filter includes a transconductance amplifier (60) and a current source (40, 42) which may be adjusted in value. The resonant frequency of the active filter may be adjusted upwards by increasing the bias current of the transconductance amplifier using a frequency trim up network (48). The resonant frequency may be adjusted downward by decreasing the bias current using a frequency trim down network (44). The trim is preferably accomplished by shorting out zener diodes (120, 122, 124, 126, 150, 152) which control the bias current of the transconductance amplifier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.