Abstract—This work presents a study of the extended counting technique for a 1.2-V micropower voice-band A/D converter. This extended counting technique is a blend of 61 modulation with its high resolution but relatively low speed and algorithmic conversion with its higher speed but lower accuracy. To achieve this, the converter successively operates first as a first-order 61 modulator to convert the most significant bits, and then the same hardware is used as an algorithmic converter to convert the remaining least significant bits. An experimental prototype was designed in 0.8- m CMOS. With a 1.2-V power supply, it consumes 150 W of power at a 16-kHz Nyquist sampling frequency. The measured peak ƒ @x C „rhA was 80 dB and the dynamic range 82 dB. The converter core including the controller and all reconstruction logic occupies about I Q I mmP of chip area. This is considerably less than a complete 61 modulation A/D converter where the digital decimation filter would occupy a significant amount of chip area. Index Terms—Analog-to-digital, extended counting, low power, low voltage. I.

This paperdesc8j es the development of the first audio ADC to fulfill the above mentioned

We develop a compensation method for continuous -time delta--sigma modulators valid for loop filters of arbitrary order. Our approach, based on variable-structure theory, accommodates multilevel quantization and dithering. Stability is rigorously proved under the assumption of infinite sampling rate and is accompanied by an analytic characterization of performance. A slight modification of the basic compensator provides a defence against parametric uncertainty through the use of variable-integrator damping.

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