A low-voltage switched-current delta-sigma modulator

This paper presents the design of a fully differential switched-current delta-sigma modulator using a single 3.3-V power-supply voltage. At system level, we tailor the modulator structure considering the similarity and difference of switched-capacitor and switched-current realizations. At circuit level, we propose a new switched-current memory cell and integrator with improved common mode feedback, without which low power-supply-voltage operation would not be possible. The whole modulator was implemented in a 0.8-/spl mu/m double-metal digital CMOS process. It occupies an active area of 0.53/spl times/0.48 mm/sup 2/ and consumes a current of 0.6 mA from a single 3.3-V power supply. The measured dynamic range is over 10 b. >