Dense wavelength division multiplexing (DWDM) and radio over fiber (RoF) are promising technologies that are able to provide unlimited transmission capacity, which meets the growing demands of bandwidth in communication systems. In this paper, an architecture for DWDM-RoF access networks uses a single Mach Zehnder modulator (MZM) to generate the mm-wave signal. This paper aims to study the effect of phase imbalance on the mm-wave signal to reduce the insertion loss in the system. It is found that the phase imbalance affects the insertion loss. The phase imbalance can be controlled by adjusting the injected phase, and the best result is collected at π 3 and 5π 12 phases.