A VCO-based analog-to-digital converter with second-order Sigma-Delta noise shaping

Abstract

A voltage-controlled oscillator (VCO) based analog-to-digital converter (ADC) utilizing Sigma-Delta (Σ-Δ) techniques for second order quantization noise shaping is presented. A custom IC prototype of this highly digital architecture achieves 60-dB signal-to-noise ratio (SNR) over a 1-MHz bandwidth with 800-MHz sampling rate. It was fabricated in a 0.18-µm 1-poly 5-metal CMOS technology.