All NPN variably controlled amplifier
US4471324A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 19, 1982 |
| Grant date | Sep 11, 1984 |
| Priority date | — |
| Expiry date | Jan 19, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03G7/002
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A signal gain controlled system comprises an operational amplifier including a feedback path between the input and output terminals of the amplifier. The system includes first variable impedance means for varying the output voltage at the output terminal of the amplifier in response to and as a function of the input current signal applied to the input terminal and a first control signal. A signal path coupled between the output terminal of the operational amplifier and the output terminal of the system includes second variable impedance means for varying the output current of the system in response to and as a function of (a) the output voltage at the output of the amplifier and (b) a second control signal. The signal gain of the system is a function of the ratio of the second and first control signals. The preferred amplifier is the type having an input resistance and a feedback resistance, wherein at least one of the resistances includes a transistor which is biased to operate in its saturated region. The gain of the amplifier is a function of the control signal applied to the base of the saturated transistor. The signal gain controlled system can be utilized with a level sensing…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.