A five-level feed-back digital-to-analog converter (DAC) in a switched
capacitor sigma-delta analog-to-digital converter has an improved
switching sequence that boosts from two to five the number of
quantization levels of the feed-back DAC. Switching sequences are used to
obtain five equally distributed charge levels C*VREF, C*VREF/2, 0,
-C*VREF/2 and -C*VREF. When summed with an input voltage, VIN, the
five-level feed-back DAC produces five equally distributed output
voltages of A*VIN+VREF, A*VIN+VREF/2, A*VIN+0, A*VIN-VREF/2 and
A*VIN-VREF, where A is gain, VIN is the input voltage, and VREF is the
reference voltage.