A 1.25MHz Bandwidth 86.4dB SNDR third-order VCO-based ADC design

VCO-based ADC is a promising candidate in advanced process because of its features of highly digital and scaling friendly. This work presents a novel 3rd-order noise shaping VCO-based ADC. The proposed architecture cascades 3 VCOs to achieve 3rd-order noise shaping and puts them in a closed loop to suppress the VCO nonlinearity. The 3rd-order noise shaping is employed in the proposed architecture so that the requirement of a high over-sampling ratio (OSR) is relaxed while maintaining a high resolution. The architecture has been verified in MATLAB Simulink.