A Highly-Digital VCO-Based Analog-to-Digital Converter Using Phase Interpolator and Digital Calibration

Abstract

A first-order time-based modulator Delta Sigma using voltage-controlled oscillator (VCO) is presented. The proposed modulator employs phase interpolation technique to enhance the time resolution of the VCO and digital calibration to improve the linearity of the VCO tuning curve. The proposed modulator, implemented in 0.13 mu m CMOS process, achieves 55 dB peak signal-to-noise ratio and 52.5 dB peak signal-to-noise-and-distortion ratio at 600 MHz sampling frequency for 20 MHz input bandwidth and consumes 14.3 mW.