Regulation and Control of Electromagnetic Field in Radio-Frequency Circuits and Systems

Since the first demonstrations of radio-frequency (RF) circuits, the physics of the electromagnetic (EM) field and its regulation and control with codesigned circuits, have become essential competencies of RF circuit designers. Leveraging advanced regulation or control methods, numerous high-performance circuits have been developed at RF and millimeter-wave (mm-wave) frequencies. Three main methods of electromagnetic regulation have been widely utilized, namely, the separation of electric and magnetic coupling paths, the manipulation of electromagnetic energy through the coupling of multiple tanks or multiple resonators, and the regulation of electromagnetic fields in air cavities or meta-substrates. The separated coupling paths of electric and magnetic fields provide guidance for designing a high-performance filter topology with a quasielliptical response through additional zeros. The manipulation of the EM field through electrical and magnetic intercouplings of multitanks or multiresonators, such as are used in oscillators, power amplifiers (PAs), etc., results in remarkable power efficiency, size reduction, and wide bandwidth. The regulation of electromagnetism through an air cavity, patterned substrate, or metasubstrate reduces dielectric losses and size, especially when using a substrate integrated suspended line (SISL) platform. Many excellent circuits have been reported based on SISL with low loss, high integration, and self-packaging. Here, we present state-of-the-art cases that demonstrate the benefits of EM field regulation and control.