A Time-Based Bandpass ADC Using Time-Interleaved Voltage-Controlled Oscillators

Abstract

In this paper, a bandpass analog-to-digital converter (ADC) based on time-inverleaved oversampled ADC is introduced. Unlike previous delta-sigma bandpass ADCs that require accurate digital-to-analog converters and high-speed analog circuits, the proposed architecture provides bandpass function by time-interleaving first-order voltage-controlled-oscillator (VCO)-based ADCs. The use of VCO-based ADC has the advantage that its resolution is determined by the time resolution rather than the voltage resolution, thus making it attractive for future low-voltage CMOS processes. The performance of the proposed ADC is theoretically analyzed and simulated in ideal condition, as well as in nonideal condition, in the presence of nonlinearity, sampling clock jitter, and mismatch.