Degradation of Alias Rejection in Continuous-Time Delta-Sigma Modulators by Weak Loop-Filter Nonlinearities

被引：3

作者：

Manivannan, Saravana ^{[1
]}

Pavan, Shanthi ^{[1
]}

机构：

[1] IIT Madras, Madras 600036, Tamil Nadu, India

来源：

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS | 2018年 / 65卷 / 10期

关键词：

Oversampled; filtering; mixing; time-variant; integrator; aliasing; CLOCK JITTER;

D O I：

10.1109/TCSI.2018.2826443

中图分类号：

TM [电工技术]; TN [电子技术、通信技术];

学科分类号：

0808 ; 0809 ;

摘要：

Implicit anti-aliasing is a remarkable property of continuous-time delta-sigma modulators employing a timeinvariant loop filter. It turns out that weak nonlinearity of the operational transconductance amplifier (OTA) used in the input integrator, in conjunction with the DAC pulse shape and OTA parasitics can greatly degrade the alias rejection of the modulator. The authors report and analyze this hitherto undiscovered mechanism. The theory is borne out by measurement results from a fourth-order single-bit filtering delta-sigma modulator designed in a 65-nm CMOS process. The alias-rejection of the modulator, which is expected to he about 160dB, is degraded to around 70dB by weak OTA nonlinearity and OTA parasitics.

引用

页码：3207 / 3215

页数：9

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