Bandpass filter sigma-delta analog-to-digital converter, e.g. for radio receiver, has two cascaded bandpass filters with first receiving feedback via digital-to-analog converter and control module and second direct from another converter

摘要

The analog-to-digital converter (1) has two bandpass filters (2, 3) connected in cascade and each having a summing stage at its input to apply feedback from a quantizer (4) via digital-to-analog converters (DACs). The first DAC (5) receives its feedback via a dynamic element matching (DEM) control module (7) which provides a second-order noise-shaping characteristic and linearizes the converter. The second DAC (6) receives its feedback signal directly from the quantizer. Preferably the band-pass filters are second-order types implemented using switched capacitors.