250W Power Amplifier with the BLF548 for 100 - 450 MHz

The BLF548 is a balanced N-channel enhancement mode vertical D-MOS transistor in a SOT262 package, especially designed for use in wideband amplifiers up to 500 MHz. The transistor is capable to deliver 150 W nominal output power at a supply voltage of 28 Volts. Due to the low output capacitance the attainable bandwidth will exceed 300 MHz.

A balanced transistor was chosen in order to reduce the second harmonic from transmitter (due to the push-pull effect) and to reduce the number of required components. The criteria for chosen MOSFETs over bipolar transistors are; high power gain, high load mismatch capabilities, low noise and easy biasing.

Schematic Circuit

Printed Circuit Board (PCB)  and Layout

Download BLF548 Application Note