Tunable Inductors Using Integrated Vanadium Dioxide Phase Change Thin Films

Li, Liangyu; Wang, Weisong; Shin, Eunsung; Subramanyam, Guru

doi:10.1155/2018/3468017

Cited by 3 publications

(8 citation statements)

References 22 publications

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“…Further due to their original geometry the inductors exhibit a tuning range of 77% (improving the 55% in 37 or 32% in 38 ) and have a Q max_on / Q max_off ratio of 0.87 unlike 0.27 in our previous work 37 . It is worth pointing out that the inductor while facing the limited conductivity levels of VO 2 on SiO 2 /Si substrates reveals a 2.33 better Q max_on value in in respect to other VO 2 based reconfigurable inductors such as the SiO 2 /Sapphire inductors reported in 51 where the conductivity levels of VO 2 exceed 300.000 S/m.…”

Section: Introductionmentioning

confidence: 85%

3D Smith charts scattering parameters frequency-dependent orientation analysis and complex-scalar multi-parameter characterization applied to Peano reconfigurable vanadium dioxide inductors

Müller

Moldoveanu

Asavei

et al. 2019

Sci Rep

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Recently, the field of Metal-Insulator-Transition (MIT) materials has emerged as an unconventional solution for novel energy efficient electronic functions, such as steep slope subthermionic switches, neuromorphic hardware, reconfigurable radiofrequency functions, new types of sensors, terahertz and optoelectronic devices. Employing radiofrequency (RF) electronic circuits with a MIT material like vanadium Dioxide, VO2, requires appropriate characterization tools and fabrication processes. In this work, we develop and use 3D Smith charts for devices and circuits having complex frequency dependences, like the ones resulting using MIT materials. The novel foundation of a 3D Smith chart involves here the geometrical fundamental notions of oriented curvature and variable homothety in order to clarify first theoretical inconsistencies in Foster and Non Foster circuits, where the driving point impedances exhibit mixed clockwise and counter-clockwise frequency dependent (oriented) paths on the Smith chart as frequency increases. We show here the unique visualization capability of a 3D Smith chart, which allows to quantify orientation over variable frequency. The new 3D Smith chart is applied as a joint complex-scalar 3D multi-parameter modelling and characterization environment for reconfigurable RF design exploiting Metal-Insulator-Transition (MIT) materials. We report fabricated inductors with record quality factors using VO2 phase transition to program multiple tuning states, operating in the range 4 GHz to 10 GHz.

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Section: Introductionmentioning

confidence: 85%

3D Smith charts scattering parameters frequency-dependent orientation analysis and complex-scalar multi-parameter characterization applied to Peano reconfigurable vanadium dioxide inductors

Müller

Moldoveanu

Asavei

et al. 2019

Sci Rep

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show abstract

“…Our designs realized a larger inductance value while maintaining a similar Q factor compared to our previous work in Ref. 7. Recently our research group has been focusing on the reconfigurable technologies that are feasible to be implemented and favorable to conventional micromachining techniques.…”

mentioning

confidence: 60%

“…Recently our research group has been focusing on the reconfigurable technologies that are feasible to be implemented and favorable to conventional micromachining techniques. [4][5][6][7][8][9][10][11][12][13] Over the years, we have developed a good understanding of employing thin films phase change material such vanadium dioxide in RF devices such as an RF switch and preliminary investigation of tunable inductors. Vanadium dioxide (VO 2 ) based tunable inductor offers advantages of faster switching speed, smaller size, easier fabrication, and lower cost.…”

mentioning

confidence: 99%

Experimental Demonstration of Vanadium Dioxide Phase Change Thin Film Based Tunable Spiral Inductors

Shin

Attariani

et al. 2020

ECS J. Solid State Sci. Technol.

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In this paper, a tunable spiral inductor integrated with vanadium dioxide (VO2) thin film on coplanar waveguide (CPW) transmission line is proposed. The tunable inductance is achieved by using the reversible, thermally controlled VO2 thin film. VO2 is one of metal to insulator phase transition (MIT) materials, which can be a potential solution for reconfigurable RF/microwave wireless communication systems. The VO2 based tunable inductors were fabricated on the sapphire substrate. A model is used to study the fingerprints of MIT and verify the nature of transition in the film. The scattering parameter measurements are taken in the frequency range from 10 MHz to 8 GHz with 801 points. The equivalent circuits have been used to characterize the behavior of tunable inductors and extract the equivalent component values, which show excellent matching to the measured S parameters. The measured results have shown an inductance tunability of 35.24% (3.856 nH−2.498 nH) at 4 GHz.

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“…The quality factor of an inductor is most commonly defined as (11) -by grounding its second port [23][24][25][28][29][30]. It is usually evaluated until x changes sign and becomes negative.…”

Section: Applications In Reconfigurable Inductors With Vanadium Dioxi...mentioning

confidence: 99%

“…In order to prove the utility of our CAD implementation, we show that, while grounding the second port of newly fabricated Vanadium dioxide two port inductors [22], one may get the Q-frequency dependency directly from the S 11reflection coefficient parameter, thus avoiding classical 2D Qfrequency plots previously employed by us [22][23] or other authors [24][25], in these types of evaluations. The proposed visualization on the 3D Smith chart proves its effectiveness for passive circuits, especially when quality factors do not exceed big values [22][23][24][25], being particularly useful for Vanadium dioxide temperature variations studies on Q-where Q degrades as temperature increases, but potentially applicable in all inductors frequency dependent factor evaluations. Here we test the temperature dependence of Q for fabricated inductors with VO 2 by sweeping it from 25 °C to 50 °C-directly from the vector network analyser with the newly developed technique.…”

Section: Introductionmentioning

confidence: 98%

3D Smith Chart Constant Quality Factor Semi-Circles Contours for Positive and Negative Resistance Circuits

et al. 2020

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The article firstly proves that the constant quality factor (Q) contours for passive circuits, while represented on a 2D Smith chart, form circle arcs on a coaxal circle family. Furthermore, these circle arcs represent semicircles families in the north hemisphere while represented on a 3D Smith chart. On the contrary, it then shows that, the constant Q contours for active circuits with negative resistance form complementary circle arcs on the same family of coaxal circles in the exterior of the 2D Smith chart. Moreover, we reveal that these constant Q contours represent complementary semicircles in the south hemisphere while represented on the 3D Smith chart for negative resistance circuits. The constant Q semicircles implementation in the 3D Smith chart computer aided design (CAD) tool is then successfully used to evaluate the quality factor variations of newly fabricated Vanadium dioxide inductors, directly from their reflection coefficient, as the temperature is increased from room temperature to 50 degrees Celsius (°C). Thus, a direct multi-parameter frequency dependent analysis is proposed including Q, inductance and reflection coefficient for inductors. Then, quality factor direct evaluation is used for two tunnel diode small signal equivalent circuits analysis, allowing for the first time the direct analysis of the Q and input impedance on a 3D Smith chart representation of a circuit, while including negative resistance.

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Tunable Inductors Using Integrated Vanadium Dioxide Phase Change Thin Films

Cited by 3 publications

References 22 publications

3D Smith charts scattering parameters frequency-dependent orientation analysis and complex-scalar multi-parameter characterization applied to Peano reconfigurable vanadium dioxide inductors

3D Smith charts scattering parameters frequency-dependent orientation analysis and complex-scalar multi-parameter characterization applied to Peano reconfigurable vanadium dioxide inductors

Experimental Demonstration of Vanadium Dioxide Phase Change Thin Film Based Tunable Spiral Inductors

3D Smith Chart Constant Quality Factor Semi-Circles Contours for Positive and Negative Resistance Circuits

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