A Time-Interleaved Continuous-Time<tex>$DeltaSigma$</tex>Modulator With 20-MHz Signal Bandwidth

Abstract

This paper presents the first implementation results for a time-interleaved continuous-time DeltaSigma modulator. The derivation of the time-interleaved continuous-time DeltaSigma modulator from a discrete-time DeltaSigma modulator is presented. With various simplifications, the resulting modulator has only a single path of integrators, making it robust to DC offsets. A time-interleaved by 2 continuous-time third-order low-pass DeltaSigma modulator is designed in a 0.18-mum CMOS technology with an oversampling ratio of 5 at sampling frequencies of 100 and 200 MHz. Experimental results show that a signal-to-noise-plus-distortion ratio (SNDR) of 57 dB and a dynamic range of 60 dB are obtained with an input bandwidth of 10 MHz, and an SNDR of 49 dB with a dynamic range of 55 dB is attained with an input bandwidth of 20 MHz. The power consumption is 101 and 103 mW, respectively