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

概要

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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) 1bit pipeline stages instead of using the conventional radix-2 1.5bit/1bit 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.