Tunable Active Inductors for Next-Generation Wireless and Biomedical Systems

The existing trend of miniaturization, energy efficiency and functional reconfigurability in the electronics of the modern era has prompted an absolute merging of radio-frequency (RF) integrated circuit design with digital health. The core of this revolution is a positively influences a very innocent but high-energy building block, the active inductor, ainositive element which is executed by transistors, capacitors, and feedback networks in normal CMOS technology. In contrast to a passive inductor, with its massive silicon footprint, values that cannot be varied after device assembly and a relatively small quality factors, the active inductor has electronic tunability, a compact inductor footprint, and can be easily integrated with the complicated semiconductor technology. This rare combination of qualities is what has made active inductors not just circuit-level curiosities, but to next-generation welfare not only wireless systems, but biomedical systems as well.
Edited book is arranged in the form of two complementary and highly interwoven theme which gives the dual natures of modern microelectronics of circuit innovation and impact system-level.
Part I explores the theory, design trends and performance limits of active inductors in CMOS. Starting with the original C topology of gyrator, the story follows decades of progress, including the initial feedback-resistance and cascode improvements, to recent advances in the so-called differential floating inductors, with negative-resistance compensation. The descriptions in these chapters of how modern designs can scale to unprecedented levels in terms of quality factors (beyond 2500 in others), tuning ranges in the inductance (into the nanoshenrier) and resilience to process-voltage-temperature co-variability, all on highly scaled CMOS nodes, are interesting. The inductor is not the only component of the discussion it also has applications in reconfigurable RF front-ends, tunable bandpass filters, low-noise amplifiers, voltage-controlled oscillators, and multi-impedance matching networks which are fundamental to 5G/6G and multi-standard transceivers.
However, the real performance of a technology is never determined by its actual performance, but rather by its ability to address real-life problems. This understanding is the logical connection to Part II in which the emphasis is not on silicon anymore, it now centers on society; it is not about circuit parameters, but patient outcomes. The book, in this case, examines RF innovations as the ability to empower the new generation of connected healthcare systems. More than simply another RF circuit, active inductor, and the reconfigurable front-end such as should be enabled by active inductors, open the door not only to a new domain of applications, but to a new domain of applications that is clever, implantable, and battery-free medical electronics. They turn out to be the facilitators of RFID-based biosensors of cardiovascular care, intelligent prostheses, and implantable diagnostics. They enable the medical implants to process energy independently in the form of RF energy harvesting and wireless power transfer, which means that the battery change is not needed in chronic-care implants. They hardware platforms are programmable, ranging in power consumption, size, and complexity, and include wearable patches powered by ultra-low-power MCUs and FPGAs in real-time neural interfaces, that execute biosignals on the edge. Importantly, and most importantly, they function in an environment of insecurity, privacy, and regulatory oversight, where cyber security is not a secondary consideration, but a matter of life and death.
The combination of both of these aspects shows a sensational synergy: the active inductor has ceased being a passive substitute, it has become an entry point to intelligent, adaptive, and patient-centered technologies. The book covers the entire range of dilemmas and opportunities in the interface of microelectronics, communications, and digital health, including the physics of synthetic inductance to the ethics of data privacy.
We wish that the work should not only be a record of the condition of art but also be a guiding influence on the young engineers and clinicians that will design systems not only technically brilliant but also with human effects.