HIGH-POWER HIGH-GAIN VD-MOSFET OPERATING AT 900 MHz.

A VD-MOSFET (vertical double-diffused MOSFET) capable of delivering output power of 100 W at 900 MHz has been developed. It offers a gain of 8 dB and drain efficiency of 45%. The double diffusion self-aligned to the gate allows the devices to control the formation of the submicrometer channel essential for high transconductance, hence high gain, with minimum gate-to-source capacitance (C//g//s). The device utilizes MoSi//2 for both gate electrodes and shield plates imbedded beneath the CVD oxide in the gate pad region. A low resistivity gate reduces the extra power dissipation to drive the gate, while the shield plate lowers the gate-to-drain capacitance (C//g//d) to half. A maximum output power has been realized by the 12 blocks of VD-MOSFETs. They are mounted on two BeO plates packaged with internal input matching circuits, and the power is measured in a push-pull amplifier.