Double sampled switched capacitor low pass multirate filter for a .SIGMA..DELTA. D/A converter
US6140951A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 14, 1998 |
| Grant date | Oct 31, 2000 |
| Priority date | — |
| Expiry date | Sep 14, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M3/502
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A .SIGMA..DELTA. digital/analog converter includes a signal reconstructing multirate low pass filter realized as a switched capacitor fully differential, double sampled structure. The input stage of the filter employs only two sampling capacitors, switched alternately on the two inputs of the stage. The input stage further includes two delay circuits (z.sup.-1) in the feed line of the bitstream towards one of the two inputs of the multistage SC filter. The zeroes introduced in the transfer function reduce the noise energy in the vicinity of frequencies f.sub.s /2.sup.n, preserving the SNR even with a relatively large mismatch between the capacitors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.