A High Isolation 0.15μm Depletion-Mode pHEMT SPDT Switch Using Field-Plate Technology

A high isolation GaAs microwave switch has been successfully developed using field-plate technology, which is effective to improve the isolation. The developed wideband SPDT switch shows a greater than 40 dB isolation before 10 GHz and also achieves good performance at higher frequency. A GaAs-based pseudomorphic high electron mobility transistors (pHEMTs) in which the field-plate (FP) metal is supplied with various biases was developed and evaluated experimentally to determine their dc and rf performance. Owing to the depth modulation of the field-plate-induced depletion region at various field-plate biases, the intrinsic devices were influenced by the tunable V_FP. This technique is easy to apply, based on standard p HEMT fabrication.