VCO Enabled Quantizer in Continuous-Time Sigma Delta ADC

The purpose of this book is to design a fully functional first-order VCO-based sigma-delta modulator. This book presents transistor-level circuit design and output simulation of first-order sigma-delta modulator along with its various components like loop filter, VCO quantizer, and 1- bit DAC. The modulator was designed using 0.18um CMOS technology for operation at 1.8V. CMOS technology was chosen due to its advantages of low power consumption and smaller layout area can be achieved. In this design, the maximum average power consumption of the VCO quantizer is 3.8mW. The simulation results show the performance of modulators in transistor level and circuit design that are compatible with each other where output was generated successfully in transistor-level circuit design along with its waveforms. A voltage-controlled oscillator (VCO) based analog-to-digital converter (ADC) is time-based architecture with a first-order noise-shaping property, which can be implemented using a VCO and design circuits. It also analyzes the performance of VCO-based ADCs in the presence of nonidealities. Based on this analysis, design criteria for determining parameters for VCO-based ADCs are described.