A 5-10 GHz 15-W GaAs MESFET amplifier with flat gain and power responses

A 5-10 GHz 15-W GaAs MESFET amplifier has been developed. It utilizes a multisection maximally flat impedance transformer whose length is designed to become a quarter wavelength at the highest frequency of the design band to achieve flat gain and flat power responses over a wide bandwidth. With the use of this transformer, the amplifier has achieved a linear gain of 9/spl plusmn/1 dB, a P1 dB of 41.8/spl plusmn/1 dBm, and a power-added efficiency of 27.5/spl plusmn/7.5% over 5-10 GHz, which demonstrate the highest power-bandwidth product ever achieved by high-power amplifiers using GaAs MESFET's, PHEMT's or HBT's.