A Single-Supply 84 dB DR Audio-Band ADC for Compact Digital Microphones

Huy-Binh LE  Sang-Gug LEE  Seung-Tak RYU  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E95-C   No.1   pp.130-136
Publication Date: 2012/01/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E95.C.130
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electronic Circuits
Keyword: 
electret capacitor microphone (ECM),  digital microphone,  audio ADC,  

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Summary: 
A 20 kHz audio-band ADC with a single pair of power and ground pads is implemented for a digital electret microphone. Under the limited power/ground pad condition, the switching noise effect on the signal quality is estimated via post simulations with parasitic models. Performance degradation is minimized by time-domain noise isolation with sufficient time-spacing between the sampling edge and the output transition. The prototype ADC was implemented in a 0.18 µm CMOS process. It operates under a minimum supply voltage of 1.6 V with total current of 420 µA. Operating at 2.56 MHz clock frequency, it achieves 84 dB dynamic range and a 64 dB peak signal-to-(noise+distortion) ratio. The measured power supply rejection at a 100 mVpp 217 Hz square wave is -72 dB.