NPN bipolar circuit topology for a tunable transconductance cell and positive current source
US5726600A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 17, 1996 |
| Grant date | Mar 10, 1998 |
| Priority date | — |
| Expiry date | Jan 17, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/0444
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An active filter circuit component includes an all NPN bipolar tunable Gm cell and a positive current source (PCS) for supplying common mode current. The tunable Gm cell includes a fixed Gm cell having transconductance G.sub.f, a current divider and recombination circuit that together effectively multiply G.sub.f by a tuning factor .alpha., where -1.ltoreq..alpha..ltoreq.1, without effecting the cell's common mode current I.sub.cm. The PCS includes a pair of unity gain inverting single ended amplifiers that are connected in antiparallel across a pair of matched resistors. Alternately, the resistors can be connected across the inverting and non-inverting sides of a differential amplifier. A constant voltage is applied across the resistors to supply I.sub.cm, while maintaining a common mode resistance of R/2 and a differential mode resistance approaching infinity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.