Key distortion issues and their solutions in direct-conversion transmitters for today´s mobile communication systems

In the wireless communication systems, owing to the increasing demands for high data rate and high efficiency, several practical challenges arise in the design of direct-conversion transmitters (DCTs) for system-on-chip (SoC) or system-in-package (SiP) applications. According to the existing literatures, power amplifier (PA) nonlinearity and local oscillator (LO) pulling are the most critical factors to deteriorate the transmit signal quality. In this work, the above two issues are carefully investigated so as to improve the resultant distortion of the DCT output signal.