A high-power high-gain VD-MOSFET operating at 900 MHz

A new vertical double-diffused MOSFET (VD-MOSFET) capable of delivering output power of 100 W at 900 MHz has been developed. It offers the gain of 8 dB and the drain efficiency of 45 percent. The double diffusion self-aligned to the gate allows the devices to control the formation of the submicrometer channel essential for the high transconductance, hence the high gain, with minimum gate-to-source capacitance (Cgs). The device utilizes MoSi2for both gate electrodes and shield plates imbedded beneath the CVD oxide in the gate pad region. Low resistivity gate reduces the extra power dissipation to drive the gate, while the shield plate lowers the gate-to-drain capacitance (Cgd) to half. A maximum output power has been realized by the 12 blocks of VD-MOSFET´s. They are mounted on the two BeO plates packaged with internal input matching circuits, and the power is measured in a push-pull amplifier.