A 10b 50MS/s 90nm CMOS skinny-shape ADC using variable references for CIS applications

This work proposes a skinny-shape 10b 50MS/s 90nm CMOS four-step pipeline ADC for various CIS applications. The proposed ADC converts analog signals in variable signal-swing ranges of 1.12 to 1.60Vp-p into low voltage-based digital data. The proposed on-chip I/V reference circuits generate the required variable reference voltages with a fixed common-mode level using a single external control voltage. The prototype ADC implemented in a 90nm CMOS process shows a maximum SNDR and SFDR of 55.1dB and 65.6dB, respectively. The ADC with an active die area of 0.23mm² consumes 17.5mW at 50MS/s using dual supply voltages of 2.5V for analog and 1.2V for digital.