Voltage controlled variable gain circuit
US4516081A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 27, 1982 |
| Grant date | May 7, 1985 |
| Priority date | — |
| Expiry date | Sep 27, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03G1/0023
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A voltage controlled variable gain circuit suitable for construction as an integrated circuit includes a first current divider comprised of two NPN transistors; a second current divider comprised of two NPN transistors, a control voltage for setting the gain of the circuit being supplied to the bases of a transistor of each current divider; an operational amplifier for producing a first signal in response to an input current, and output currents from each current divider; first and second current sources, each producing a constant current; a first differential amplifier comprised of two NPN transistors having emitters supplied with the constant current from the first current source and the collector of one transistor supplying a drive current to the first current divider; and a second differential amplifier comprised of two NPN transistors having emitters supplied with the constant current from the second current source and the collector of one transistor supplying a drive current to the second current divider; the steady state currents through both first and second current dividers being controlled to a value less than one-half the value of the constant current from the first and …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.