Class-AC VCO and Continuous-Time Low-pass Sigma Delta ADC for Automatic Control EMI Reduction

Abstract

Integrated continuous-time low-pass sigma delta (Σ-Δ) analog to digital converter (ADC) and Class A with Class C low consumption control oscillator (VCO) is designed and implemented in tsmc 0.18μm CMOS 1P6M process. A spread-spectrum clock generator (SSCG) with direct modulation on the voltage controlled oscillator (VCO) is presented. The proposed sigma delta ADC and VCO in SSCG can generate an accurate triangular modulation on the output frequency and thus it can achieve high electromagnetic interference (EMI) reduction with a smaller spreading ratio as compared with existing designs for automatic control application.