A low-supply-voltage high-power-handling stacked SPDT switch based on feedforward capacitors

Abstract

In this letter, a 30MHz-3GHz 10W single pole double throw (SPDT) switch with 3.3V low supply voltage fabricated in 0.5um GaAs pHEMT technology process is presented. A feedforward capacitor pair is introduced in each stacked FET, which makes full use of the advantages of high breakdown voltage (VBDG) of GaAs process under low supply voltage and enhances the power handling of each FET unit. Under specific power level, switch with reduced number of stacked FETs and low insertion loss are achieved. Meanwhile, uniform-partial-voltage stacked FET units with different gate width is applied to the switch design, which solves the problem of non-uniform partial voltage caused by parasitic capacitance(Cpd) between stacked FETs. As a result, the power handling of the switch is higher than 40dBm under continuous wave. Besides, the switch designed in this letter achieves 0.5dB insertion loss at 1.5GHz and the input and output return loss is less than -18dB at the whole frequency band. The test results verify the accuracy of the theoretical analysis.