Design of a 14-bit continuous-time delta-sigma A/D modulator with 2.5MHz signal bandwidth.

摘要

In recent years, there has been growing interest in both industry and academia to use continuous-time (CT) Delta-Sigma A/D converters for wideband wireless and wireline communication applications.; So far no reported CT Delta-Sigma A/D modulator achieves 14-bit or higher dynamic range (DR) with more than 2MHz signal bandwidth (equivalently 4MS/s). This dissertation presents the realization of a continuous-time (CT) Delta-Sigma A/D modulator providing 80.5dB DR and 85dB DR with 5MS/s output data rate in a 2.5V 0.25mum CMOS process. The modulator has a single-stage dual-loop architecture allowing large quantizer delay. A 17-level quantizer is used to increase resolution and non-return-to-zero DACs are adopted to reduce clock jitter sensitivity. Capacitor tuning is utilized to overcome time-constant variation. On-chip self-calibration is implemented to suppress DAC nonlinearity. Combining techniques to address various design challenges, the modulator consumes 50mW with 60MHz sampling rate.