A single-channel, 600Msps, 12bit, ringamp-based pipelined ADC in 28nm CMOS

A pipelined ADC is presented that exploits the low but very constant (over output swing) open-loop gain characteristic of the ring amplifier (ringamp) to achieve high SFDR in low-voltage nanoscale CMOS designs. A dynamic ringamp biasing scheme using CMOS resistors and an active ringamp-based common-mode feedback (CMFB) are also introduced. The implemented prototype achieves 56.3dB SNDR and 69.2dB SFDR at 600Msps, consuming 14.2mW from a 0.9V supply, resulting in a Figure-of-Merit (FoM) of 44.3fJ/conv.-step.