A low-power and low-complexity continuous-time Gm-C based delta-sigma modulator for WCDMA/UMTS

This article describes the implementation of a continuous-time Delta-Sigma modulator for WCDMA/UMTS in wireless communication. The Delta-Sigma modulator employs a Gm-C based integrator to form a fourth-order noise-shaping loop. The modulator samples at 160MHz and has an over-sampling ratio of 40 in 2MHz bandwidth. To reduce power consumption and design complexity, single-bit quantisation is employed. The modulator is implemented in 0.25m 1-ploy 5-metal CMOS technology and has an area of 0.13mm2. The modulator can achieve 70.7dB of signal-to-noise-plus-distortion-ratio and 74dB of dynamic range. Finally, the modulator consumes 3.5mW of power with a reduced power supply of 1.8V.