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This paper presents a third order continuous time current mode ΣΔ modulator for WLAN 802.11b standard applications. The proposed circuit utilized feedback architecture with scaled and optimized DAC coefficients. At circuit level, we propose a modified cascade current mirror integrator with reduced input impedance which results in more bandwidth and linearity and hence improves the dynamic range. Also, a very fast and precise novel dynamic latch based current comparator is introduced with low power consumption. This ultra fast comparator facilitates increasing the sampling rate toward GHz frequencies. The modulator exhibits dynamic range of more than 60 dB for 20 MHz signal bandwidth and OSR of 10 while consuming only 914 μW from 1.8 V power supply. The FoM of the modulator is calculated from two different methods, and excellent performance is achieved for proposed modulator.

This paper presents a dual-quantization SC Sigma-Delta Modulator intended for A/D Conversion in ADSL applications., ESPRIT Project 29261 MIXMODEST.

This paper explores the use of ΣΔ techniques for A/D conversion exceeding 1-MHz signal bandwidth. A cascade modulator architecture is proposed which combines single-bit and multi-bit quantization to obtain more than 12-b Dynamic Range (DR) with an oversampling ratio of only 16, and with neither calibration nor trimming required. Measurements from a 0.7mm CMOS prototype show 74dB DR in 1.1-MHz signal band at 35.7-MHz clock rate, with a power consumption of 55mW from a 5-V supply., This work has been supported by the European Union, under ESPRIT Project 8795-AMFIS.