A 0.13µm CMOS 78dB SNDR 87mW 20MHz BW CT ΔΣ ADC with VCO-based integrator and quantizer
نویسندگان
چکیده
Voltage-controlled oscillator (VCO) based ADCs have become a topic of great interest due to the unique and attractive signal-processing properties they offer in the design of oversampling converters. Assuming a ring-oscillator structure, the outputs of a VCO toggle between two discrete levels (VDD and GND) like a CMOS digital gate, enabling simple multibit quantization using Dflip-flops. Since only one VCO output phase transitions at a given sampling instant while all others saturate to the positive/negative supply, quantization is robust to flip-flop voltage offsets and metastability, and has guaranteed monotonicity. Furthermore, the VCO behaves as a CT integrator in that its output phase is proportional to the time integral of the applied control voltage. As long as it oscillates, the VCO output phase accumulates endlessly, implying that it is also an integrator with infinite DC gain.
منابع مشابه
A 0.13[mu]m CMOS 78dB SNDR 87mW 20MHz BW CT [Delta Sigma] ADC with VCO-based integrator and quantizer
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