Transconductance cell with improved linearity
US5311088A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 23, 1992 |
| Grant date | May 10, 1994 |
| Priority date | — |
| Expiry date | Jul 23, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/0433
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Analog filters may be conveniently implemented in MOS technology by the use of "transconductance cells". Each cell includes stages each having a pair of current paths, with each path comprising a current source and input transistor. The gain of each stage is set by a transistor connected across the current path, with the transconductance of this transistor being controlled by its gate voltage. In the inventive technique, a transconductance cell comprising two input stages utilizes inputs to each input stage that are in-phase rather than complementary, as in prior-art designs. The inputs to the second input stage are then each balanced (out of phase) with respect to the inputs to the first input stage. Higher linearity is obtained, with the common-mode signal being cancelled by the summation of currents supplied by the input stages to the common output stage. A biquadratic filter conveniently implements this technique, with other applications being possible.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.