A 0.8mW 5bit 250MS/s time-interleaved asynchronous digital slope ADC

Slope and digital-ramp converters are normally limited to very low sampling rates, since they require a digital counter at a highly oversampled clock rate. In this work, an asynchronous digital slope architecture is introduced that only requires a non-oversampled clock, thus enabling a much higher speed of operation. At the same time, the low complexity and the inherent accuracy of the slope-architecture enable very good power-efficiency without using calibration techniques. A 2-channel time-interleaved 5 bit asynchronous digital slope ADC was implemented in a 90 nm CMOS technology. The measured prototype achieves an ENOB of 4.6 bit, while operating at 250 MS/s and consuming 0.8 mW from a 1 V supply.