Method and apparatus for matching common mode output voltage at a switched-capacitor to continuous-time interface
US6317068A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 23, 1999 |
| Grant date | Nov 13, 2001 |
| Priority date | — |
| Expiry date | Aug 23, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45441
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for matching common mode output voltage at a switched-capacitor to continuous-time interface. An active continuous time summation circuit is used at the output of the switched-capacitor stage to derive the common mode level that is at the output of the switched-capacitor stage. This derived signal is filtered to remove any noise component remaining in it, and is then used as the reference common mode signal in the continuous time stage. This forces the output common mode, and hence the input common mode of the unity gain amplifier stage, to track the common mode output of the switched-capacitor stage. This adaptive tracking eliminates the common mode interface error, which could be present and could vary from die to die (due to parasitic variations). This technique ensures proper tracking of the DC levels between the negative and the positive terminals of the unity gain amplifier, which is essential for low distortion operation of the amplifier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.