This paper presents a Quadrature/Polar hybrid digital transmitter architecture (HB-TX). Coarse polar modulation is realized by combining the main DPA and a low-resolution selector, while a fine quadrature modulation is realized by the asymmetrical quadrature recombination of main and auxiliary DPA. In this way, it achieves high-efficiency and fast modulation while does not a high-speed and high-resolution phase modulator. Simulation results show it delivers 17.6-dBm average output power with 17.4% average PAE and the EVM is -35.87 dB, when modulating a 64-QAM signal with 80-Msym/s symbol rate and 6.5-dB peak average power rate (PAPR).