An architecture of Delta-Sigma A-to-D converters using a voltage controlled oscillator as a multi-bit quantizer

This paper proposes a new architecture for an oversampling Delta-Sigma Analog-to-Digital converter utilizing a voltage controlled oscillator (VCO), called a VCO DS A-to-D converter. The converter consists of a VCO, a counter, an analog integrator, and a feedback D-to-A converter. Through functional and circuit simulations, an SNR of over 50 dB was obtained at a 5 MHz signal bandwidth and 400 MHz sampling frequency using 0.6 μm CMOS technology. This architecture is highly suitable for implementation with deep sub-μm CMOS devices that can attain improved switching speeds and reduce power dissipation during low voltage operation. It provides wideband oversampling A-to-D converters for video and wireless signals and a low voltage system-on-a-chip solution for multi-media applications