To increase bandwidth first, the IC housing structure is investigated using full-wave electromagnetic field simulators. A suitable package is based on the concept of `chip-size-cavity package', by which the parasitic resonance is suppressed and the isolation characteristics between input and output ports are greatly improved. Second, a frequency-de-pendent biasing termination is employed for the drain-line of the amplifier to improve gain degradation at frequencies below 10Ghz. With a package developed for 10Gbps optical transmission systems, fatal degradation of isolation characteristics occurs around 20GHz. The degradation mechanism is analyzed using a full-wave electromagnetic field simulator. This simulator analyzes complex three-dimensional structures and is suited for finding scattering parameters of packages in a wide frequency range. The measured frequency characteristics of the module are shown. Operation is stable with gain flatness within 1.5dB, and 3dB bandwidth of 58GHz. No significant package-induced degradation of return losses is observed. Chip connections are ribbon wires less than 300μm long. Small ripples remain above 25Ghz due to impedance mismatching at the connections. Mismatching could be reduced by using finer connections, such as bumps.