Optimized Co-Design of Delta Sigma Modulators and Fir-DACs for High Speed Transmitters

Delta sigma modulators (DSMs) are a very attractive solution to build flexible high resolution transmitters needed for future massive multiple-input multiple-output (mMIMO) systems. The main challenge in this architecture is its out-of-band (OOB) noise which can be addressed by using FIRDACs. This paper proposes a joint design of the DSM and FIRDACs. The coefficients of the latter are chosen using a multiobjective optimization approach which takes into account the DAC and the DSM noise. The proposed solution is simulated for a 400 MHz 4-Channel signal. Compared to a classical design approach with similar complexity, it achieves 2.86 dB and 16.19 dB improvements for respectively the adjacent and the alternate channel power ratio and error vector magnitude (EVM) of 1.02.