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  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E95-A   No.2   pp.471-478
Publication Date: 2012/02/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E95.A.471
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
Category: 
Keyword: 
continuous-time,  delta sigma modulator,  harmonic distortion,  tuning system,  

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Summary: 
This paper presents a low distortion 3rd-order continuous-time delta-sigma modulator for a worldwide digital TV-receiver whose peak SNDR is 69.8 dB and SNR is 70.2 dB under 1 V 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 0.18 pJ/conv-step.