A High Speed, Switched-Capacitor Analog-to-Digital Converter Using Unity-Gain Buffers

Satomi OGAWA  Kenzo WATANABE  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E76-A   No.6   pp.924-930
Publication Date: 1993/06/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Papers Selected from 1992 Joint Technical Conference on Circuits/Systems,Computers and Communications (JTC-CSCC'92))
Category: Methods and Circuits for Signal Processing
Keyword: 
switched-capacitor circuits,  A/D converter,  unity-gain buffer,  CMOS comparator,  

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Summary: 
A cyclic analog-to-digital (A/D) converter is developed which accomplishes an n-b conversion in n/2 clock cycles. The architecture consists of two 1-b quantizers connected in a loop. A CMOS design of the 1-b quantizer is given to evaluate the performance of the A/D converter when implemented using presently available process. Spice simulations and error analyses show that a resolution higher than 10-b and a sampling rate up to 1.4 Msps are attainable with a 3-µm CMOS process. A prototype converter breadboarded using discrete components has confirmed the principles of operation and error analyses. The device count and the power consumption are small compared to those of a successive-approximation A/D converter. A chip area required for the CMOS implementation is also small because only four unit capacitors are involved. Therefore, the architecture proposed herein is most suited for high accuracy, medium speed A/D conversion.