Tunable Impedance Transformer Based on J-Invertors for Load Modulated Power Amplifier

This article explores the circuit design procedure for tuneable impedance transformers utilizing lumped elements J-inverters. Proposed device based on a capacitive Π-circuit of the J-inverter facilitates the electronic tuning of wave impedance. With the ability to electronically tune wave impedance, the performance and efficiency of various electronic systems and devices can be enhanced. The required range of tuneable capacitance to achieve the desired tuning impedance range is obtained based on load–pull analysis of the power amplifier that employed for load modulation techniques. The required range of tuning capacitors of the Π-circuit is determined using analytical analysis, which is discussed in this article. The impedance transformer schematic model based on real component parameters is described in detail. The tuneable impedance transformer layout has been designed and fabricated. The main tuned element of the circuit is the varactor. The measured results demonstrate that the tuneable impedance transformers can effectively adjust the impedance of a circuit within the range of 4Ω to 30Ω at 2.5 GHz.