Filtering Power Amplifier With Up to 4th Harmonic Suppression

Unlike conventional conception that power amplifier and filter are regarded as two separate components and designed separately, this paper presents a high efficiency power amplifier with filtering capability, which is called filtering power amplifier. The proposed power amplifier integrates a bandpass filter as output matching network so that entire size is reduced to some extent. The filter will play the role of filtering and impedance matching simultaneously, and thus high-order harmonics are suppressed for output of the filtering power amplifier. For demonstration, an example of filtering power amplifier was designed, fabricated and measured. The measurement shows that it is featured by highly-selective bandpass response and good out-of-band performance. As high as 46.2 dB suppression can be achieved and extended over the forth-order harmonic. The example also retains the advantages of high efficiency and output power. The maximum output power can reach 40.5 dBm, and the maximum power-added efficiency is as high as 62%.