Enhanced Q current mode active filter
US4843343A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 4, 1988 |
| Grant date | Jun 27, 1989 |
| Priority date | — |
| Expiry date | Jan 4, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/1213
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A current mode active filter includes a differential amplifier, having two transistors, and a current mirror, having two transistors, connected into a feedback loop. The phase shift of the loop is controlled by one or two grounded capacitors and bias current sources connected to forward bias the base-emitter junctions of the transistors. The frequency of the filter is controlled by varying the dynamic resistances of the base-emitter junctions with the bias current sources. The current mirror increases loop gain, thereby enhancing the Q of the circuit. Improved dynamic range and large-signal performance can be achieved by the addition of two transistors to the current mirror circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.