A 5/sup th/ order /spl Sigma//spl Delta/ modulator for GSM/WCDMA dual-standard wireless receivers

A MASH 2-1-1-1 structure with a 5 level internal quantizer at the last stage is designed for a very-low-IF GSM/zero-IF WCDMA receiver. According to the different signal bandwidth and dynamic range requirements, this sigma delta modulator is reconfigured to achieve the required resolution with less power consumption. In GSM mode, only the first stage (2^nd order SigmaDelta ADC) is turned on to achieve 76dB DR with oversampling ratio of 64 and bandwidth of 400kHz; in WCDMA mode, all the stages are turned on, together with a 5 level quantizer at the last stage, to achieve 66dB dynamic range with oversampling ratio of 8 and bandwidth of 5MHz. For other standards, like Bluetooth, Zig-bee, ADSL etc., this multi-standard SigmaDelta modulator can be easily reconfigured as MASH 2-1 or 2-1-1 structures to achieve different requirements from different standards. The design was implemented in TSMC 0.35mum CMOS process with 3.3V power supply