Low-harmonic distortion in single-ended and push-pull class E power amplifier by using slotted microstrip lines

In this work, a very low-harmonic distortion with high power-added efficiency (PAE) power amplifier (PA) with slotted microstrip lines is reported. The circuit is a push-pull class E amplifier, terminated with defected structures to improve the spectrum purity and efficiency. The relationship of the second and third harmonic to the fundamental is 70 and 54 dBc, respectively. The amplifier is developed with HBT medium power transistors. The circuit works at 1.8 GHz obtaining a PAE close to 60%, delivering an output power of 24 dBm with a power gain of 13.3 dB.