An oscillatory noise-shaped quantizer for time-based continuous-time sigma-delta modulators

In this paper, a new type of an oscillatory noise-shaped quantizer (NSQ) for time-based continuous-time sigma-delta modulators is presented. The proposed NSQ is composed of an oscillatory voltage-to-time converter and a polyphase sampler. Using Tustin's transformation method and through the approximation of the comparator gain, a linearized model of the NSQ is introduced. This way, a novel realization of the first- and second-order NSQ is presented. Its implementation is based on fully passive continuous-time filters without needing any amplifier or power consuming element. The ploy-phase sampler inside the NSQ is based on the combination of a time-to-digital and a digital-to-time converter. The layout of the proposed NSQ is provided in Taiwan Semiconductor Manufacturing Company 0.18m complementary metal-oxide-semiconductor 1P6M technology. The verification of the proposed NSQ is done via investigating both the system level and postlayout simulation results. Leveraging the proposed NSQ in an Lth-order time-based continuous-time sigma-delta modulator enhances the noise-shaping order up to L+2, confirming its superior effectiveness. This makes it possible to design high performance and wideband continuous-time SDMs with low power consumption and relaxed design complexity.