Abstract
A high efficiency power amplifier for digital-television-broadcasting transmitter is in demand. In order to carry out a high efficient power amplifier, the doherty amplifier circuit was used. And a gallium nitride high electric mobility transistor (GaN HEMT) was also used as an amplifier device. In the experimental results, compared to the efficiency of more than 18% of the conventional product, the efficiency was improved to more than 30%.