Variable gain amplifier having linear-in-decibel transconductance
US7262660B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 18, 2007 |
| Grant date | Aug 28, 2007 |
| Priority date | — |
| Expiry date | Jan 18, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45702
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A variable gain amplifier includes a variable resistor, a first MOS transistor and a second MOS transistor. The variable resistor has one end coupled to a ground. The first MOS transistor with transconductance 2gm amplifies a first differential input signal to provide a first current between an output node and other end of the variable resistor. The second MOS transistor with transconductance gm amplifies a second differential input signal to provide a second current between the output node and the ground. The variable resistor can be implemented using a MOS transistor operating in a linear region. The variable gain amplifier has an exponentially varying output current responsive to adjusting a gate voltage of the MOS transistor. Therefore, the transconductance of the variable gain amplifier has a linear-in-decibel characteristic.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.