A 10-bit 25-MS/s 1.25-mW Pipelined ADC With a Semidigital Gm-Based Amplifier

A semidigital Gm-based amplifier is proposed for a low-power pipelined analog-to-digital converter (ADC). The amplifier performs a class-AB operation by smoothly changing between a comparator-like semidigital driver and a continuous-time high-gain amplifier according to the input voltage difference. A 10-bit pipelined ADC with 2.5-bit/stage architecture is implemented in a 0.13-
$\mu\hbox{m}$
CMOS. The ADC consumes 1.25 mW at a sampling rate of 25 MS/s and achieves a Nyquist-rate figure-of-merit of 139 and 232 fJ/c-s without and with power consumption from a resistor ladder, respectively.