Harmonics suppression investigations of pHEMT single-pole-single-throw switches using multi-gate structures

In this study, multi-gate GaAs pseudomorphic high electron mobility transistor (pHEMT) single-pole-single-throw (SPST) microwave switches were implemented and characterized for high power operation. The switch size is not only minimized by employing the compact zigzag layout structure but also with gate finger parallel bar structure for increasing power handling capability. The measured RF and harmonic powers suppression results was analyzed, the parameters of OFF-state (gate bias = −3 V) small-signal model were extracted for single-, dual-, triple- and quadruple-gate switch devices individually. Under ON-state (gate bias = 0 V) operation, the insertion loss performance is slightly worse due to the increasing of gate number and results in the rising ON-state resistance (RON). However, the isolation performance can be enhanced by 4 dB from the single-gate device to the triple-gate one. The quadruple-gate device demonstrates only 0.2 dB improvement in isolation performance than the triple-gate one, but it slows the improvement of harmonic suppression level owing to the increasing of the gate-to-gate coupling capacitance.