A low-noise dual-gate GaAs MESFET for UHF TV tuner

Demonstrates a new dual-gate GaAs MESFET specially designed for a low-noise UHF TV tuner. The device has been designed under the philosophy as follows: (1) to reduce |S/SUB 11/| and input Q of the field-effect transistor (FET) at the smallest expense of the low-noise feature inherent in GaAs MESFET´s (2) to obtain automatic gain control (AGC) and cross-modulation performances compatible with those of a conventional Si MOS tetrode. The optimized pattern geometry satisfying the above philosophy was obtained through theoretical and experimental studies. The FET, of which minimum noise figure (NF) value is as low as 0.9 dB at 1 GHz, was compatible with an Si MOS tetrode in a conventional tuner circuit owing to the small |S/SUB 11/| and low input Q values obtained. The AGC and cross-modulation performance were also satisfactory.