Takeshi Fukui

Low-voltage operation GaAs spike-gate power FET with high power-added efficiency

A GaAs power FET with a spike-gate has been developed for high-efficiency operation under extremely low supply voltage less than 1.5 V. The spike-gate provides both low on-resistance of 2.2 /spl Omega//mm and high transconductance of 180 mS/mm without reducing the output impedance or increasing the gate resistance. The implemented device achieved an output power of 31.5 dBm with 70% power-added efficiency at a frequency of 900 MHz. It should be noted that the present device kept PAE of 60% even at a bias of 0.5 V, which is the lowest voltage ever attained.

High power-added efficiency and low distortion GaAs power FET employing spike-gate structure

Abstract A GaAs power FET employing a spike-gate structure was developed for the high efficiency and low distortion operation under the extremely low supply voltage of 1.5 V. This spike-gate FET is featured by an unique gate structure that has almost zero effective gate length. The spike-gate provides both the low on-resistance of 2.2Ω mm −1 and the low drain conductance of 5 mS mm −1 . Maximum frequency of oscillation ( f max ) is over 30 GHz that is estimated from S-parameter under the supply voltage of 1.5 V. The decrease of the f max is smaller for the spike-ate FET than for the conventional one as the decrease of supply voltage. In π/4-shift QPSK modulation system, the implemented device achieved the output power of 31.0 dBM with 52% power-added efficiency and −51 dBc adjacent channel leakage power at the frequency of 925 MHz under the drain supply voltage of 1.5 V.