Generalized architecture of concurrent dual-band transmitter for spectrum aggregation system

The concurrent transmission and reception of the signals in different frequency bands are required for the mobile terminals in IMT-Advanced systems to support spectrum aggregation systems. The authors have proposed a new transmitter architecture that enables the concurrent transmission of two separate frequency bands. The architecture is based on delta-sigma (ΔΣ) modulation, which converts a non-constant envelope signal into a constant one. This enables the transmitter to employ a high efficiency switching power amplifier. This paper proposes a generalized architecture that handles the situation where one carrier frequency of the transmission signals is not an integral multiple of the other carrier frequency. To demonstrate the effectiveness of the proposed architecture, the results of a simulation in which QPSK signals were concurrently transmitted in two bands are presented.