Non-binary Pipeline Analog-to-Digital Converter Based on β-Expansion

Tomonari KATO
Kazuyuki AIHARA

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E96-A    No.2    pp.415-421
Publication Date: 2013/02/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E96.A.415
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
non-binary AD conversion,  β-expansion,  pipeline ADC,  switched-capacitor circuits,  multiply-by-β MDAC,  

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This paper proposes a pipeline analog-to-digital converter (ADC) with non-binary encoding technique based on β-expansion. By using multiply-by-β switched-capacitor (SC) multiplying digital-to-analog converter (MDAC) circuit, our proposed ADC is composed by radix-β (1 < β < 2) 1 bit pipeline stages instead of using the conventional radix-2 1.5 bit/1 bit pipeline stages to realize non-binary analog-to-digital conversion. Also with proposed β-value estimation algorithm, there is not any digital calibration technique is required in proposed pipeline ADC. The redundancy of non-binary ADC tolerates not only the non-ideality of comparator, but also the mismatch of capacitances and the gain error of operational amplifier (op-amp) in MDAC. As a result, the power hungry high gain and wide bandwidth op-amps are not necessary for high resolution ADC, so that the reliability-enhanced pipeline ADC with simple amplifiers can operate faster and with lower power. We analyse the β-expansion of AD conversion and modify the β-encoding technique for pipeline ADC. In our knowledge, this is the first proposal architecture for non-binary pipeline ADC. The reliability of the proposed ADC architecture and β-encoding technique are verified by MATLAB simulations.