Design theory of broadband high‐efficiency continuous Class EF power amplifier based on new continuous factor

Summary This paper presents the design theory for continuous Class EF power amplifier (PA). This theory facilitates the implementation of broadband designs for high‐efficient Class EF PA. First, combining with the switching operating conditions and harmonic tuning technique, the drain waveform expressions of Class EF PA is derived. The corresponding third harmonic component can get its impedance in form of pure reactance, which simplifies the matching process while maintaining the efficiency. Second, a new continuous factor (CF) dedicated to the continuous Class EF PA can be obtained, with applying waveform mapping concept. The new CF expands the impedance point of Class EF PA into the impedance space. This greatly enhance the flexibility of broadband design. With this new theory, the design of broadband Class EF PA becomes very simple. As a verification, a Class EF PA operating at 2.4–3.8 GHz has been designed using CREE GaN HEMT CGH40010F. The PA can achieve the gain of 9.1–11.2 dB, the output power of 39.1–41.2 dBm, the PAE of 66.3%–74.1%, and the DE of 69.5%–76.2%. Both simulated and measured data show very good consistency and prove the rationality and validity of the proposed theory.