| 摘要 |
A sigma-delta modulator has a chopper voltage reference providing a reference signal having a clock dependent offset voltage, a single-bit or a multi-bit digital-to-analog converter (DAC); a plurality of capacitor pairs; a plurality of switches to couple any capacitor pair to an input or reference signal; and a control unit controlling sampling through said switches to perform a charge transfer in two phases wherein any capacitor pair can be selected to be assigned to the input or reference signal, wherein after a plurality of charge transfers a gain error cancellation is performed by rotating the capacitor pairs cyclically, and wherein a DAC output value and a reference offset state define switching sequences wherein each switching sequence independently rotates said capacitor pairs and wherein at least one switching sequence is selected depending on a current DAC output value and a current reference offset state. |
