A Low Distortion 3rd-Order Continuous-Time Delta-Sigma Modulator for a Worldwide Digital TV-Receiver

Koji OBATA; Kazuo MATSUKAWA; Yosuke MITANI; Masao TAKAYAMA; Yusuke TOKUNAGA; Shiro SAKIYAMA; Shiro DOSHO

doi:10.1587/transfun.E95.A.471

Special Section on Analog Circuit Techniques and Related Topics

A Low Distortion 3rd-Order Continuous-Time Delta-Sigma Modulator for a Worldwide Digital TV-Receiver

Koji OBATA, Kazuo MATSUKAWA, Yosuke MITANI, Masao TAKAYAMA, Yusuke TOKUNAGA, Shiro SAKIYAMA, Shiro DOSHO

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Keywords: continuous-time, delta sigma modulator, harmonic distortion, tuning system

JOURNAL RESTRICTED ACCESS

2012 Volume E95.A Issue 2 Pages 471-478

DOI https://doi.org/10.1587/transfun.E95.A.471

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Abstract

This paper presents a low distortion 3rd-order continuous-time delta-sigma modulator for a worldwide digital TV-receiver whose peak SNDR is 69.8dB and SNR is 70.2dB under 1V power supply. To enhance SNDR performance, the mechanisms to occur harmonic distortions at feedback current-steering DAC and flash ADC have been analyzed. A low power tuning system using RC-relaxation oscillator has been developed in order to achieve high yield against PVT variations. A 3rd-order modulator with modified single opamp resonator contributes to cost reduction by realizing a very compact circuit. Reduction schemes of the distortions enabled the modulator to achieve FOM of 0.18pJ/conv-step.

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