Amplifier and filter having variable gain and cutoff frequency controlled logarithmically according to digital code
US8884693B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Dec 13, 2012 |
| Grant date | Nov 11, 2014 |
| Priority date | — |
| Expiry date | Feb 25, 2033 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45522
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A variable gain amplifier circuit is provided. The circuit includes an operational amplifier for amplifying and outputting an input signal according to a cutoff frequency and a gain, a feedback resistor for changing a first resistance according to a first digital control code value which determines the cutoff frequency, and an input resistor for changing a second resistance according to a second digital control code value which is determined based on a difference of the first digital control code value and a gain code value. The gain is determined by a ratio of the first resistance and the second resistance and linearly changes on a decibel (dB) basis according to the first digital control code value, the cutoff frequency is inversely proportional to the first resistance and linearly changes on a log scale, and the variable gain can be easily set using the control code.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.