
Demystifying Switched-Capacitor Circuits
182
Cyclic ADCs
A cyclic (or algorithmic) A/D converter, like its D/A counterpart introduced in
Section 5.3, uses the same analog circuitry to perform the conversion in a recycling
fashion. Thus, the cyclic ADC is typically chosen for applications that require a low
power consumption and a small chip area.
A conceptual schematic of an M-bit cyclic ADC is shown in Figure 5.12. Note
that the cyclic ADC looks almost identical to the 1-bit pipelined stage shown in
Figure 5.9, except for the feedback from the subtraction unit to the input sampling
switch.
The cyclic ADC operates as follows. During the fi rst cy ...