Investigation on the Effect of Different Form Factors on the Performance of Miniaturized Transformers

Miniaturized transformers have become essential components to enable the realization of compact, efficient, and cost-effective electronics systems. Depending on the selected substrate and technology, planar micro-transformers can be integrated directly on a silicon device, included as stand-alone components in a System-in-Package (SiP) approach, or mounted directly on PCB. In this paper, an investigation on the effect of different form factors, defined as the ratio between the shorter and longer substrate sides, on the performance of miniaturized transformers is presented. Relevant performance indicators are defined, and a test case is numerically analysed, varying the form factor from 1 to 0.46, with 0.01 steps. The presented results show marginal variations on both voltage ratio and efficiency for form factors ranging from 1 to 0.8, while potentially severe reduction in efficiency up to 10 % can be expected for form factors smaller than 0.5.