A continuously trimmable comparator-based gain stage

A method for continuous trimming of a comparator-based gain stage is proposed and analyzed. Trimming of the gain error is achieved by adding a constant current source which charges only one of the two capacitors determining the circuit gain. This approach removes converter non-linearity when used in a cyclical analog-to-digital converter. The offset error can be trimmed by adjusting the precharge or reference voltage. For a converter affected by mismatch, simulated results on the transistor- and on the functional level confirm that an ideal transfer characteristic is restored using the proposed method.