Architecture and filtering requirements for fully digital multi-radio transmitters

This paper gives filtering requirements for an all-digital transmitter and identifies technical and technological challenges. Herein, we highlight trade-offs implied by such a transmitter. This work targets a flexible and low power consumption transmitter, taking into account advantages of sub-micron CMOS technologies. We focused on a multi-radio transmitter for cellular standards such as GSM, WCDMA and LTE for mobile applications. Simulation results point out the mandatory frequency replicas management caused by up-sampling process and the so needed filtering before emission to be dimensioned. Specifications of the filter to be design are given after an overall fully digital architectures study.