A 50-MHz multibit sigma-delta modulator for 12-b 2-MHz A/Dconversion |
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Authors: | Brandt B.P. Wooley B.A. |
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Affiliation: | Center for Integrated Syst., Stanford Univ., CA ; |
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Abstract: | The authors examine the application of oversampling techniques to analog-to-digital conversion at rates exceeding 1 MHz. A cascaded multibit sigma-delta (ΣΔ) modulator that substantially reduces the oversampling ratio required for 12-b conversion while avoiding stringent component matching requirements is introduced. Issues concerning the design and implementation of the modulator are presented. At a sampling rate of 50 MHz and an oversampling ratio of 24, an implementation of the modulator in a 1-μm CMOS technology achieves a dynamic range of 74 dB at a Nyquist conversion rate of 2.1 MHz. The experimental modulator is a fully differential circuit that operates from a single 5-V power supply and does not require calibration or component trimming |
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