A 5.5GS/s 28mW 5-bit flash ADC with resonant clock distribution

A 65nm CMOS 5.5GS/s non-interleaved 5-bit flash ADC with resonant clocking is presented. An on-chip 0.77nH inductor resonates the entire clock distribution network to achieve energy-efficient operation. The ADC occupies 0.035mm² and consumes 28mW when operating at 5.5GHz, yielding 396fJ per conversion step. The clock network dissipates only 10.7% of total power, consuming 54% lower energy over CV². By comparison, in a typical flash ADC design, 30% of total power is clock-related. From measurement results, ENOB is 4.56b and 4.11b with f_in at 440MHz and 2.04GHz, respectively.