A dual-VCO-based quantizer with highly improved linearity and enlarged dynamic range

In this paper, a novel structure of dual-VCO-based quantizer is introduced to significantly improve the VCO linearity. Compared with the precedent methods, the proposed structure can accomplish the linearity without sacrificing the intrinsic DEM function of the VCO-based quantizer, which greatly simplifies the structure of the circuit implementation. Moreover, a passive adder is introduced in this paper, instead normal active adder; the power consumption can be optimized. Besides, due to the dual-VCO structure, the dynamic range of the modulator can be greatly enlarged. A first order continuous-time (CT) sigma-delta (ΣΔ) modulator with the proposal quantizer is designed and simulated in 65 nm CMOS process. The performance of the modulator can reach 83.7/83 dB SNR/SNDR with 10MHz bandwidth and 1V supply voltage.