Improved sigma-delta type analog-to-digital converter and method

DETAILED DESCRIPTION The present invention provides a method and architecture for high channel count multiplexing into a sigma delta converter for low frequency measurement applications by partitioning the digital filtering.
In one preferred embodiment, a sigma delta converter's high frequency sampling rate stabilizes low frequency signals, and the filtering process has two steps: a higher frequency filtering action that filters out internally generated noise sources but maintains a high throughput for the converter, and a lower frequency filtering action implemented on an individual channel basis using signal averaging that is tuned to filter out externally generated line noise.