On the RF subsampling continuous-time ΣΔ downconversion stage for multistandard receivers

This paper deals with the design and analysis of a new RF subsampling downconversion front-end assigned to propose a multistandard receivers for next wireless generation standards. The RF subsampling front-end is based on continuous time (CT) bandpass ΣΔ modulator with sine-shaped feedback DAC. Much attention is given to frequency sampling selection and non idealities in subsampling CT-bandpass ΣΔ modulator. Thus, the mainly jitter effect on SNR degradation is investigated. Simulation results for a dual-mode GSM and WCDMA receiver based on RF subsampling fourth order CT-bandpass ΣΔ modulator show that the proposed topology can improve the SNR output measurement with low sampling rate.