An analog-to-digital converter (ADC) circuit (400) and method of operation are disclosed. In some aspects, the ADC circuit (400) may include a plurality of channels (500), a gain calibration circuit (420), and a time-skew calibration circuit (430). Each of the plurality of channels (500) may include an ADC (520), a switch (510) configured to provide a differential input signal to the ADC (520), a calibration device (530), a multiplier (540), and a pseudorandom bit sequence (PRBS) circuit (550) to provide a pseudorandom number (PN) to the switch (510), to the calibration device (530), and to the multiplier (540). In some embodiments, the calibration device (530) may include first and second offset calibration circuits (531-532) coupled in parallel between a de-multiplexer (D1) and a multiplexer (M1) that alternately route signals to the first and second offset calibration circuits (531-532) based on the pseudorandom number (PN).