A simple method for tunable load impedance matching network of power amplifier

In this article, we proposed one simple method which achieves variable load impedance. By this method, without utilizing load pull tuner, the errors caused by various reasons, such as parasitic effect at the lumped components and active devices, can be corrected. We designed and fabricated one Class-AB amplifier to demonstrate our simple method by adjusting a shunt variable capacitor and inductor added at the input and output of the load matching network respectively. Before correcting the circuit, comparing the measured maximum PAE (Power Added efficiency) of the power amplifier (40.21% at 37.70 dBm output power) with the simulated PAE (52.96% at 40.35 dBm output power), the performance of this amplifier was not as what simulation predicted. After optimizing the circuit with our method, we obtained the maximum PAE reached 50.63% and the maximum output power increased to 40.10 dBm which more agree with the simulated result than the result before the correction.