A 3.3mW ΣΔ modulator for UMTS in 0.18μm CMOS with 70dB dynamic range in 2MHz bandwidth

Abstract

A quadrature fourth-order, continuous-time, modulator with 1.5-b quantizer and feedback digital-to-analog converter (DAC) for a universal mobile telecommunication system (UMTS) receiver chain is presented. It achieves a dynamic range of 70 dB in a 2-MHz bandwidth and the total harmonic distortion is 74 dB at full-scale input. When used in an integrated receiver for UMTS, the dynamic range of the modulator substantially reduces the need for analog automatic gain control and its tolerance of large out-of-band interference also permits the use of only first-order prefiltering. An IC including an and modulator, phase-locked loop, oscillator, and bandgap dissipates 11.5 mW at 1.8 V. The active area is 0.41 mm in a 0.18m 1-poly 5-metal CMOS technology.