Method and apparatus for calibrating a multi-bit delta-sigma modular
US5257026A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 17, 1992 |
| Grant date | Oct 26, 1993 |
| Priority date | — |
| Expiry date | Apr 17, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M3/424
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A calibration method and apparatus to calibrate for non-linearities in a multi-level delta-sigma modulator (12) includes a calibration multiplexer (10) on the input for selecting in a calibration mode a zero voltage for input to the delta-sigma modulator (12). The delta-sigma modulator (12) has three levels, +1, 0, -1, the +1 level input to a processor (32) and the -1 level input to a processor (34). The processor (34) has the output thereof input to an compensation circuit (14) that offsets the value generated by the -1 processor (34) by a coefficient .delta.. The output of the compensation circuit (14) is then input to the minus input of a summation junction (36), which also receives the output of the processor (32), the output of summation junction (36) providing the digital output. The processors (32) and (34) are realized with a separate accumulator that switches between an associated filter coefficient and ground, the filter coefficient stored in a ROM (35). The .delta. coefficient is stored in a block (16) and is generated during a calibration cycle by a .delta. processor (39). The .delta. processor (39) receives the output of the compensation circuit (14) and the digital ou…
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