Adjustable gain differential amplifier
US5198780A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 20, 1992 |
| Grant date | Mar 30, 1993 |
| Priority date | — |
| Expiry date | Apr 20, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F3/45766
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A differential amplifier avoids gain fluctuations due to process differences and changes in temperature and allows adjustability of the gain and associated frequency characteristics to desired gain values. The amplifier comprises a pair of load transistors coupled to a pair of differential input transistors. A pair of biased current source transistors assure a constant current through the differential transistors, and a pair of bias transistors supply a constant bias to the source of the load transistors. The gain is varied by varying the voltage supplied to the gates of the two load transistors. The voltage supplied to the load transistors is varied by varying the current supplied through a second pair of bias transistors. A number of current source transistors coupled in parallel vary the voltage through the second pair of bias transistors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.