A high performance DC-20 GHz SPDT switch in a low cost plastic QFN package

This paper reviews the design and measurements of a DC-20 GHz GaAs SPDT (single-pole-double-throw) switch with state-of-the art insertion loss, isolation and power handling in a low cost plastic QFN (Quad Flatpack Non-lead) package. To reduce the performance degradation introduced by the plastic QFN package, 3D EM (electromagnetic) modelling was used to characterize the interconnection between the MMIC die and the package. The packaged switch yields 1.7 dB maximum insertion loss and 40 dB minimum isolation from DC to 20 GHz. The comparison between this result and the data measured from the MMIC bare die shows no significant performance deterioration caused by the package. The switch utilizes M/A-COM's 0.5 µm pHEMT (Pseudomorphic High Electron Mobility Transistor) process which is based on an AlGaAs/InGaAs/GaAs material system.