Switch-embedded opamp-sharing MDAC with dual-input OTA in pipelined ADC

A switch-embedded opamp-sharing multiplying digital-to-analogue converter (MDAC) with dual-input-differential-pair operational transconductance amplifier (OTA) is proposed to eliminate the non-resetting and successive-stage crosstalk problems in the conventional opamp-sharing technique. A 10-bit 80 MS/s pipelined analogue-to-digital converter (ADC) is implemented in a 0.18 m CMOS process by using the proposed MDAC. Compared with a traditional opamp-sharing ADC, the measured signal-to-noise ratio is improved from 55.9 to 60.1 dB and the spurious free dynamic range is improved from 66 to 76 dB without any additional power or area consumption or clock phase.