A Charge-Redistribution Phase-Domain ADC Using an IQ-Assisted Binary-Search Algorithm

Phase-domain Analog-to-Digital Converters (Ph-ADCs) have been considered for power-efficient implementation of body-area network transceivers employing phase demodulation. Conventional implementations of the Ph-ADCs, which work based on a full-flash zero-crossing algorithm, use linear resistive/current combiners to determine the thermometer digital code of the signal phase. These architectures suffer from high-accuracy requirements, high-circuit complexity, and high-power consumption. Therefore, in this paper, a new IQ-assisted binary-search algorithm is proposed for implementing the Ph-ADC. The proposed Ph-ADC architecture avoids employing the power-hungry linear combiner. Moreover, for an N-bit Ph-ADC, the proposed algorithm requires only N +1 comparisons, whereas the conventional full-flash counterpart demands 2^N-1 comparisons. Based on the proposed architecture, two different 5-bit charge-redistribution Ph-ADC s are designed and one of them is fabricated in a standard 0.18-μm CMOS technology. The prototype achieves an ENOB of 4.85 bits at 1 MS/s, while dissipating 12.9 μW from a 1.2-V supply.