Reconfigurable Digital Delta-Sigma Modulation Transmitter Architecture for Concurrent Multi-Band Transmission

This paper presents a reconfigurable delta-sigma modulation (DSM) architecture for concurrent multi-band transmission. The reconfigurability in terms of carrier spacing and the number of simultaneous carrier transmission is useful for applications such as carrier aggregation in 5G. This paper uses 4th order reconfigurable multi-band DSM (RMB-DSM) such that the zeros of the noise transfer function can be reconfigured to fall at multiple frequencies, where the carriers are being aggregated. The quantization noise between the transmission bands is a critical issue in the case of multi-band transmission. Therefore, a multi-band additional noise shaping (ANS) function is also introduced, which generates notches around each carrier and reduces the noise level between the multiple pass-bands. The proposed scheme has been validated in simulation, as well as in experiment for aggregating up to four 15 MHz long term evolution (LTE) signals with an overall aggregated bandwidth of 60 MHz. Measurement results show a 10-25% improvement in coding efficiency and 15-35 dB improvement in noise level near the operating frequency band using the proposed multi-band augmented noise shaping technique, as compared to the standard DSM. The corresponding improvement of 8% in the overall efficiency is observed by using the proposed multi-band augmented noise shaping technique.