A multirate low power sigma delta modulator for multi-standard mobile terminals

A new low power multimode switched-capacitor sigma delta modulator (SDM) architecture for wireless communication receivers is proposed in the paper. The proposed modulator uses a cascade 2-1-1 topology with single-bit quantizer for stability and inherent linear. The double-sampling SDM and multirate SDM are incorporated together to reduce the slewrate of the operational amplifier (OPAMP) and power dissipation. The low-distortion swing-suppressing technique is used to decrease the inband harmonic distortion. The effects of circuit nonidealities on the modulator performance are discussed. A peak SNR of 85/82/66/63/56/48 dB is achieved over a 0.2/1/2/3.84/22/28 MHz channel bandwidth for GSM/Bluetooth/GPS/WCDMA/WLAN/WiMAX mode. The simulation results demonstrate that the proposed modulator structure fulfills the performance requirements of the above mentioned mobile communication standards and confirm the effectiveness of the proposed scheme.

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