The modern wireless communication industry is demanding transceivers with a high integration level operating in the gigahertz frequency range. This, in turn, has prompted intense research in the area of monolithic passive devices. Modern fabrication processes now provide the capability to integrate onto a silicon substrate inductors and capacitors, enabling a broad range of new applications. Inductors and capacitors are the core elements of many circuits, including low-noise amplifiers, power amplifiers, baluns, mixers, and oscillators, as well as fully-integrated matching networks. While the behavior and the modeling of integrated capacitors are well understood, the design of an integrated inductor is still a challenging task since its magnetic behavior is hard to predict accurately. As the operating frequency approaches the gigahertz range, device nonlinearities, coupling effects, and skin effect dominate, making difficult the design of critical parameters such as the self-resonant frequency, the quality factor, and self and mutual inductances. However, despite the parasitic effects and the low quality-factor, integrated inductors still allow for the implementation of integrated circuits with improved performances under low supply voltage. In this chapter, the authors review the technology behind monolithic capacitors and inductors on silicon substrate for high-frequency applications, with major emphasis on physical implementation and modeling.
A monolithic InP/SOI platform for integrated photonics
