Electromagnetic Susceptibility Analysis of a Power Amplifier against Radiated and Conducted Interferences with the 3D-FDTD Method

Electromagnetic susceptibility (EMS) of a power amplifier (PA) against an interfering wave is presented. The interfering waves affect the performance of any circuit, either intentionally or from adjacent equipment. In the case of power amplifiers, this phenomenon can overdrive the PAs into the nonlinear region and if the interfering wave still exists, it can damage the PA. Therefore, circuit designers must design the circuit to be not susceptible to interfering waves, as much as possible. In this article, EMS analysis of a PA against an interfering Gaussian modulated pulse with the 3D finite difference time domain (3D-FDTD) method is presented. In this method, the transistor is replaced with an appropriate transistor nonlinear large-signal EEHEMT circuit model, and the whole circuit of the PA including the transistor circuit model, matching networks, and biasing circuits is simultaneously analyzed in the presence of radiated and conducted interferences. This method gives more accurate results than the hybrid methods that analyze the active and passive parts of the amplifier separately. This method is applied to a designed PA with Wolfspeed’s CGHV1J006D discrete GaN on SiC high electron mobility transistor (HEMT) and a hybrid method is proposed to validate the results. The results show a good agreement between the proposed and the validation method.