A method and system for controlling an analog-to-digital converter (ADC) in an observation path in a transceiver. The transceiver includes a transmit path, a receive path, and an observation path. The observation path includes an analog buffer and an observation ADC. A controller generates a control signal to control sampling events at the observation ADC to activate the observation ADC at combined uniform and non-uniform sampling instants. The controller may also generate a second control signal indicating whether digital data obtained by the observation ADC is valid or not. The digital data generated by the observation ADC at non-uniform sampling instants is indicated as invalid and digital data generated by the observation ADC at uniform sampling instants is indicated as valid. The digital data indicated as invalid may be discarded and the digital data indicated as valid is used for calibration of the transmit path or the receive path.