Anomalous Behaviors of Cut– off Frequencies in 0.5 μm GaAs Power MESFET' s

Anomalous behaviors of the cut-off frequencies in the fabricated 0.5 μm GaAs power MESFET's are possibly detected for the first time. The cut-off frequency of a GaAs power MESFET is supposed to be gradually decreased as the total gate width increases. On the contrary, the gate width increase of a GaAs power MESFET gives rise to increase of the cut-off frequency. The cut-off frequency of a GaAs power MESFET with 0.9 mm gate width is about 13 GHz, and that with 3.0 mm about 16 GHz. This anomalous behaviors in the cut-off frequency of a GaAs power MESFET could be due to the occurrence of resonance phenomena because the stray capacitances are considerably increased in a wider gate width device.