This paper presents a practical example of chip-packageboard codesign for a highly linear 3G-CDMA upconverter module. A 1.9 GHz upconverter MMIC is designed and implemented using InGaAs HBT foundry process. The goal for this MMIC design is to achieve the high linearity required in a W-CDMA system. In addition, the complete interconnect effects of package and PCB are considered rigorously by establishing their equivalent circuits with the help of the EDA EM-simulation tool. The proposed design for the upconverter MMIC adopts a Gilbert-cell mixer with emitter-degeneration to enhance the linearity performance. This MMIC is housed in a leadless 24-pin BCC package and surface-mounted onto an FR4 PCB for measuring the complete RF parameters. The simulation results from both the theoretical approach and the EDA circuit-simulation tool for this upconverter module agree quite well with the final measurement results.