Hybrid CT/DT resonation-based cascade ΣΔ modulators for broadband low-voltage applications

In this paper, two new hybrid CT/DT cascade ΣΔ modulators are proposed for use in low-voltage broadband applications. Unlike the MASH architecture, these modulators are less sensitive to amplifier DC gain of continuous-time (CT) stage and avoid the need of compensation for finite gain-bandwidth induced error in CT loop filter. The modulators also feature global resonation scheme, noise transfer function enhancement, double-sampling technique and flat and unity STFs. These techniques are combined together in novel topologies that allow increasing the resolution in nanometer CMOS high-speed applications. Behavioral simulations confirm the effectiveness of the proposed schemes.