Abstract: Comparator offset cancellation and capacitor self-calibration techniques used in a successive approximation analog-to-digital converter (SA-ADC) are described.The calibration circuit works in parallel with the SA-ADC by adding additional calibration clock cycles to pursue high accuracy and low power consumption,and the calibrated resolution can be up to 14bit.This circuit is used in a 10bit 3Msps successive approximation ADC.This chip is realized with an SMIC 0.18μm 1.8V process and occupies 0.25mm2.It consumes 3.1mW when operating at 1.8MHz.The measured SINAD is 55.9068dB,SFDR is 64.5767dB,and THD is -74.8889dB when sampling a 320kHz sine wave.

Key words: analog-to-digital converter, successive approximation, self-calibration techniques