Dithered sigma delta modulator having programmable full scale range adjustment
US5905453A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 4, 1997 |
| Grant date | May 18, 1999 |
| Priority date | — |
| Expiry date | Aug 4, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M3/494
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A sigma delta modulator (10) for use in codec applications provides dynamic range adjustment and avoids asymmetrical signal clipping. The modulator (10) has a summing circuit that sums a plurality of inputs, one of which is a dither component. The dither is programmably modifiable to provide enhanced performance. The dither is provided by a pseudo random number generator (100). The pseudo random number generator (100) has an n-bit shift register (106) coupled to a last code detect (108) to detect the end of a pseudo random number sequence. At that time, a new preset code can be loaded (110) into the shift register (106) to provide different dither characteristics. This allows the pseudo random number generator (100) to programmably determine the percentage of ones and zeros to add to the output signal. The dither output can be inverted (104) to shift the dither up or down.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.