Analysis and design of voltage-controlled oscillator based analog-to-digital converter

Abstract

This paper presents through derivation of operational principle of voltage-controlled oscillator based analog-to-digital converter(VCO-ADC). Design parameters such as VCO phase noise, linearity and the phase noise of sampling clock for VCO-ADC are defined and the effect of the parameters on VCO-ADC is analyzed. Design guide based on the analysis is also provided. This design guide illustrates for the optimum power management and design architecture for given specification of VCO-ADC. After the analysis and design guide, novel techniques to achieve high performance VCO-ADC are introduced. Sub-feedback VCO is a promising VCO architecture to enhance the time resolution of VCO as its number of phase and frequency tuning range can be independently controlled. Phase interpolation is also a feasible technique to enhance the resolution. Analysis and implementation of digital calibration to compensate for the non-linearity of VCO is also presented. The design issues and circuit detail of the VCO-ADCs using proposed techniques are introduced. Finally measurement results of the ADCs are presented.