PHEMT distributed power: amplifier adopting broadband impedance transformer

A non-uniform drain line distributed power amplifier (DPA) based on GaAs PHEMT technology and employing a broadband impedance transformer is presented. In the DPA topology, each device contributes to the overall output impedance of the amplifier. The value of the load impedance is chosen for optimal power performance across the required frequency range of the four-section PHEMT DPA with non-uniform drain line. An m-derived section is implemented at both terminations of the gate line. Each device is supplied with 5V, while a bias voltage of 0.44 V is applied to each gate, resulting in Class AB operation for the active devices. The necessary phase velocities synchronization between the gate and drain lines is achieved by adopting a non-uniform gate line design and selecting an output load equal to 12.5 ω. In order to match the entire circuit to a standard 50ω load over the broad frequency range of operation, a wide-band impedance transformer having a transformation ratio of 1:4 has been implemented