Variable gain amplifying circuit
US7489195B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 8, 2007 |
| Grant date | Feb 10, 2009 |
| Priority date | — |
| Expiry date | Aug 8, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45652
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A variable gain amplifying circuit comprises two stages, a first stage and a second stage with a common voltage-to-current converter. Each stage comprises two BJTs, two voltage controlled current sources, a variable resistor with a variable resistance, and the common voltage-to-current converter. The two BJTs construct a differential amplifier for amplifying a pair of differential signals. The variable resistor with the variable resistance is connected between the emitters of the two BJTs wherein the variable resistance of the variable resistor is represented as RE. The variable resistance RE is controlled by a control voltage Vctrl. The two voltage controlled current sources are respectively connected between the corresponding emitter of BJTs and ground. The currents respectively through the voltage controlled current sources are equal to each other and represented as IE. The current IE is controlled by the common voltage-to-current converter according the control voltage Vctrl. The variable resistance RE and the current IE of the voltage controlled current sources can be varied simultaneously by the control voltage Vctrl so as to rapidly adjust the gain of the variable gain ampli…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.