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.

High-performance analog-to-digital converters, digital-to-analog converters, and fractional- frequency synthesizers based on delta--sigma (16) modulation---collectively referred to as data converters---have contributed significantly to the high level of integration seen in recent commercial wireless handset transceivers. This paper presents a tutorial on data converters and their uses and implications with respect to wireless transceiver architectures.

Abstract—We present design considerations for low-power continuous-time 16 modulators. Circuit design details and measurement results for a 15 bit audio modulator are given. The converter, designed in a 0.18 m CMOS technology, achieves a dynamic range of 93.5 dB in a 24 kHz bandwidth and dissipates 90 Wfroma 1.8 V supply. It features a third-order active-RC loop filter, a very low-power 4-bit flash quantizer, and an efficient excess-delay compensation scheme to reduce power dissipation. Index Terms—Analog-to-digital converter (ADC), continuous time, data converter, jitter, oversampling, sigma-delta modulation.