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Described is a 14 bit 50 MS/s CMOS four-stage pipeline A/D converter (ADC)-based on a digital code-error calibration. The proposed calibration technique measures the capacitor mismatch errors of the front-end multiplying DAC (MDAC) with the back-end pipeline stages while the measured code errors are stored in memory and corrected in the digital domain during normal conversion. The calibration needs the increased power dissipation and chip area of 1.4 and 10.7 , respectively, compared to a 14 bit uncalibrated conventional pipeline ADC. The prototype ADC fabricated in a 0.18 um CMOS process occupies an active die area of 4.2 mm2 and consumes 140 mW at 1.8 V and 50 MS/s. After calibration, the measured DNL and INL of the ADC are improved from 0.69 to 0.39 LSB and from 33.60 to 2.76 LSB, respectively.
Date of Publication: October 8 2009