Global analysis for a surface wave mode HFET amplifier module at 60 GHz by EM-device co-simulation

A global analysis for a millimeter-wave amplifier module with surface wave mode transmission lines has been demonstrated. The analysis method is a co-simulation between an FDTD-based electromagnetic simulator and a semiconductor device simulator. Using this method, it is possible to consider various electromagnetic coupling between transmission lines and active devices with nonlinear characteristics. Furthermore, a semiconductor device simulation is more accurate than an approximation to a large-signal equivalent circuit. The incorporated simulation was demonstrated for a millimeter-wave amplifier module which consists of an HFET and planar dielectric transmission lines (PDTL) at 60-GHz region. The PDTL with a surface wave transmission mode has a low-loss transmission characteristic at millimeter-wave region using a low-loss ceramic substrate. However, the transmission wave on the PDTL tends to be scattered by discontinuity structures and impedance mismatching. Furthermore, it is predicted that reflected scattered waves at edges of the substrate interfere the PDTL and transistors mounted on the PDTL. Using the co-simulation technique, influence of the scattering waves was investigated in detail for the amplifier module.