A Highly Digital CCO-Based Asynchronous Analog-to-Time Converter

Abstract

This paper presents an asynchronous current controlled oscillator (CCO) based analog-to-time converter (ATC). The proposed ATC uses a ring oscillator as phase-domain integrator and quantizer. A negative feedback loop using current steering digital-to-analog converter (DAC) relaxes linearity requirement of the CCO. The ATC output is a multi-phase pulse-width modulated (PWM) signal which can be used with continuous-time digital signal processing systems. The proposed ATC is simulated in 65nm CMOS process an√d has a 59.2dB SNDR with an input-referred noise of 42.6nV/$\sqrt {{\text{Hz}}} $ over 500kHz bandwidth while consuming 11µW from 0.5V power supply.