This brief proposes a multiport transmitter front-end (MTFE) architecture to bolster the concurrent dual-band transmission while supporting the digital predistortion (DPD) processing. The proposed architecture consists of two back-to-back multiport networks driven by only one local oscillator (LO) through a multilayer power divider. The low-power LO source can effectively suppress the growth of intermodulations in/between the transmit and DPD feedback loop, thereby optimizing transmission performance. Furthermore, the architecture makes full use of the mainstream DPD architectures, like the frequency-selective (FS) method, to migrate the in-band/cross-band distortions and the adjacent channel interference (ACI) caused by the nonlinearity of the power amplifiers. In experiments, we evaluate the performance of the proposed MTFE architecture over the QAM and OFDM signals. The results consistently demonstrate excellent DPD performance under concurrent dual-band transmission.