A high-linearity single-pole-double-throw pseudomorphic HEMT switch based on tunable field-plate voltage technology

A high-isolation high-linearity GaAs pseudomorphic high-electron mobility transistor single-pole-double-throw microwave switch was developed using a tunable field-plate (FP) bias voltage technology. In this paper, a piece of FP metal was deposited between 0.15-μm-long gate and drain terminals. An extra FP-induced depletion region was generated to suppress the harmonics of switching associated with off-state operation. When switching into the on-state, the FP switch is associated with an insertion loss similar to that of the standard switch below 6 GHz. However, the isolation performance can be enhanced by 10 dB using an FP technology, which reduces the off-state capacitance that is produced by the extra FP-induced depletion region. The FP provides an additional mechanism to suppress the power of the second- and third-order harmonics in the off-state with slight on-state insertion-loss degradation.