1 Multi-Step Extended-Counting Analog-to- Digital Converters

Extended-counting A/D converters are proposed which achieve a high accuracy by performing the conversion in several cycles. During the first cycle, the circuit performs as an incremental ADC, while during the remaining ones it acts as a multi-slope counting converter. With only one opamp and a single-slope ADC, the accuracy is comparable to that of a second-order incremental ADC. A three-step A/D converter using only a single opamp and a two-slope ADC achieves an accuracy comparable to that of a third-order incremental ADC, but with much higher power efficiency. Introduction: Incremental ADC is useful for high-accuracy conversion of signals at DC or with low bandwidth [1]. To enhance the conversion speed, a higher-order modulator or extended counting may be used [2-4]. In this paper, we propose an incremental ADC with an added single- or multi-slope ADC to perform the extended counting. Wit