Utilizing Process Variations for Reference Generation in a Flash ADC

This brief presents an experimental study on how to take advantage of the increasing process variations in nanoscale CMOS technologies to achieve small and low-power high-speed analog-to-digital converters (ADCs). Particularly, the need for a reference voltage generation network has been eliminated in a 4-bit Flash ADC in 90-nm CMOS, with small-sized comparators. The native comparator offsets, resulting from the process-variation-induced mismatch, are used as the only source of reference levels, and redundancy is used to acquire the desired resolution. The measured performance of the 1.5-GS/s ADC is comparable to traditional state-of-the art ADCs and dissipates 23 mW.