A Novel Variable Inductor Using a Bridge Circuit and Its Application to a 5–20 GHz Tunable LC-VCO

Tanabe, A.; Hijioka, K.; Nagase, Hirokazu; Hayashi, Y.

doi:10.1109/jssc.2011.2108790

Cited by 54 publications

(27 citation statements)

References 14 publications

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“…However, others have described tunable inductors for RFIC applications by using interesting bridge topologies [10] or multi-tap structures [11]. Even an inductor with three taps (i.e., three quantized inductance values) can provide substantial performance benefits.…”

Section: Theorymentioning

confidence: 99%

Near-Field Wireless Power Transfer

Mercier

Chandrakasan

2015

Integrated Circuits and Systems

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Wireless power transfer links are becoming increasingly important for consumer, industrial, and medical electronic devices. There are two principal applications for wireless power transfer that require different optimization criteria: continuous power deliver (e.g., cochlear implant) and periodic charging (e.g., cellular phone). In the former case, optimizing power transfer efficiency is a metric of great importance, while in the latter case, minimizing charging time by maximizing power transfer is important. This chapter presents analytical equations that predict optimal conditions for both applications through first-principals step-bystep reflected load analysis. These equations are then used as the basis for the design of a rapid wireless ultra-capacitor charging circuit that speeds up time-to-charge by 3.7 .

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Section: Theorymentioning

confidence: 99%

Near-Field Wireless Power Transfer

Mercier

Chandrakasan

2015

Integrated Circuits and Systems

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“…This secondary reactance modulation technique can be performed dynamically to provide robustness to instantaneously changing load impedances, or it can be performed semi-statically to provide robustness against variations in coil separation distances, all while decreasing charging time. Although tunable inductors are often difficult to implement, others have described and validated such circuits for RFIC applications using interesting bridge topologies [26] or multi-tap structures [27].…”

Section: Multi-tapped Secondary Design a Theorymentioning

confidence: 99%

Rapid Wireless Capacitor Charging Using a Multi-Tapped Inductively-Coupled Secondary Coil

Mercier

Chandrakasan

2013

IEEE Trans. Circuits Syst. I

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Abstract-This paper presents an inductive coupling system designed to wirelessly charge ultra-capacitors used as energy storage elements. Although ultra-capacitors offer the native ability to rapidly charge, it is shown that standard inductive coupling circuits only deliver maximal power for a specific load impedance which depends on coil geometries and separation distances. Since a charging ultra-capacitor can be modeled as an increasing instantaneous impedance, maximum power is thus delivered to the ultra-capacitor at only a single point in the charging interval, resulting in a longer than optimal charging time. Analysis of inductive coupling theory reveals that the optimal load impedance can be modified by adjusting the secondary coil inductance and resonant tuning capacitance. A three-tap secondary coil is proposed to dynamically modify the optimal load impedance throughout the capacitor charging interval. Measurement results show that the proposed architecture can expand its operational range by up to 2.5X and charge a 2.5F ultra-capacitor to 5V upwards of 3.7X faster than a conventional architecture.

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“…Several techniques have been proposed to extend the TR of mmwave VCOs [20][21][22][23][24][25][26][27][28]. However, it is very crucial to have a solid understanding of the key limitations imposed by the scaling of CMOS technology on the realization of mm-wave LC-VCOs.…”

Section: Introductionmentioning

confidence: 99%