Research on signal integrity of transmission paths in system in packaged RF power amplifier

In order to study the signal integrity at high frequency, the system in packaged design RF power amplifier is carried out in this paper, and the three-stage cascade structure is adopted. Based on the finite element model, this paper explores the influence of BGA solder joint, transmission line and via structure on the insertion loss and return loss. Based on the orthogonal experimental design, the influence of various factors on the transmission path insertion loss and return loss is sorted by using range analysis and variance analysis. In addition, the response surface method is used to obtain a better combination of parameters in which the insertion loss and return loss of the transmission path meets the design requirements. Through the simulation and analysis of the model, the influencing factors of insertion loss range analysis are as follows: microstrip width > via pad radius > via radius > BGA solder joint maximum radial radius, and return loss range analysis is: microstrip line width > via radius > BGA solder joint maximum radial radius > via radius. The conclusion is obtained by analysis of variance that microstrip line width has a significant effect on transmission path insertion loss and return loss, while via pad radius, via pad and BGA solder joint maximum radial radius have no significant effect on transmission path insertion loss and return loss. The insertion loss of the optimized transmission path structure optimized by the response surface method increases and the return loss decreases, and the optimal parameter combination that meets the requirements of the package design is selected.