This paper presents a novel design simulation method that integrates both the layout and circuit designs in a single design platform. The layout of a power amplifier (PA) module can be optimized in seconds of simulation time. By incorporating advanced behavioral modeling techniques, the presented method is also capable of analyzing the complex digital modulation quality of a power amplifier (PA) module in much less time as compared with conventional non-integrated methods. Design examples for CDMA and Wireless LAN (WLAN) PA's are presented, showing excellent performance. The comparisons and design considerations of semiconductor and packaging technologies are also provided.