In one embodiment, digital-to-analog converter (DAC) circuit includes dual DAC units employing pseudo-return-to-zero DAC operations to reduce inter-symbol interference. Moreover, each DAC unit is implemented using complementary MOS transistors to improve conversion performance. In another embodiment, a DAC calibration scheme performs background calibration of an array of DAC circuits in continuous time using a reference DAC circuit and a spare DAC circuit. Calibration (also referred to as “trimming”) of the DAC circuit using the calibration scheme of the present invention ensures that the DAC operates with high linearity over process variations. In one embodiment, the DAC circuit and the DAC calibration scheme are applied as the feedback DAC in a continuous-time sigma-delta (CT-ΣΔ) analog-to-digital converter to realize high performance and high precision analog-to-digital conversions.