- 2 2-PHASE GAIN CALIBRATION AND SCALING SCHEME FOR SWITCHED CAPACITOR SIGMA-DELTA MODULATOR USING A CHOPPER VOLTAGE REFERENCE

摘要

The sigma-delta modulator comprises: a chopper voltage reference, a single-bit or multi-bit digital-to-analog converter (DAC) providing a reference signal having a clock dependent offset voltage; A plurality of capacitor pairs; A plurality of switches selectively coupling a pair of capacitors from the plurality of capacitor pairs to an input signal or a reference signal; Control means for controlling sampling through the switches to perform charge transfer during the two stages, wherein some of the capacitors may be selected to be assigned to the input signal or the reference signal, and by cyclically cycling the plurality of capacitor pairs, Wherein a gain error cancellation is performed after a plurality of charge transfers, the output value of the DAC and the offset state of the chopper reference voltage defining switching sequences, each switching sequence cycling independently of the plurality of capacitor pairs, The sequence is selected depending on the current output value of the DAC and the current offset state of the chopper reference voltage.