Signal processing system with baseband noise modulation and noise filtering
US6861968B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 23, 2003 |
| Grant date | Mar 1, 2005 |
| Priority date | — |
| Expiry date | Sep 23, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M7/3026
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A digital-to-analog converter (“DAC”) system utilizes notch filters and chopping modulation technology to remove l/f and other baseband noise from a baseband of a signal of interest. Chopping modulation and demodulation circuitry of the DAC operate at a chopping frequency and all harmonics equal to approximately one-half of a digital input signal sampling frequency. A notch filter attenuates signals having frequencies around the chopping frequency prior to chopping to reduce fold back of noise into the baseband due to parasitic modulation. Another notch filter attenuating signals having frequencies around twice the chopping frequency further reduces fold back of noise into the baseband.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.