Analysis and modeling of interstacked transformers for mm-wave applications

The analysis and modeling of monolithic interstacked transformers for mm-wave applications is addressed. The performance advantages of the interstacked structure are demonstrated by using the most important figures of merit for integrated transformers and a physic-based scalable lumped model is proposed. The model components are calculated with closed-form expressions that make use of geometrical and technological parameters. The accuracy of the proposed model is demonstrated by comparison with electromagnetic data in a wide frequency range. Maximum errors are below 5, 7.5, and 2% for magnetic coupling factor, quality factor, and self-resonance frequency, respectively. High accuracy is also achieved in the modeling of S-parameters up to the self-resonance frequency.