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

Müller, Andres; Moldoveanu, Alin; Asavei, Victor; Khadar, Riyaz Abdul; Codesal, Esther Sanabria; Krammer, Anna; Fernández-Bolaños, Montserrat; Cavalieri, Matteo; Zhang, Junrui; Casu, Emanuele Andrea; Schüler, Andreas; Ionescu, Adrian M.

doi:10.1038/s41598-019-54600-5

Cited by 6 publications

(43 citation statements)

References 48 publications

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“…By using the stereographic projection (9), we can get images of the coaxal circles on the 3D Smith chart located on the unit space sphere (surface) centered in the origin (0,0,0) [19][20][21][22].…”

Section: B 3d Smith Chart Representation Of Constant Q Semicirclesmentioning

confidence: 99%

“…Considering our previous work [22], the inductance can be represented in the 3D space via a homothety over the 113 parameter using (13) where ( ) represents the normalized extracted inductance. Fig.…”

Section: Applications In Reconfigurable Inductors With Vanadium DImentioning

confidence: 99%

“…For the on state it can be seen clearly that these values do not decrease below 4 for the frequency range displayed. Fig 8 (b) adds the frequency representation proposed in [22] over the previous render, offering their dynamical view as frequency is swept. Fig 8 (c) shows the extracted inductance displayed over them, using a centre projection for each point.…”

Section: Applications In Reconfigurable Inductors With Vanadium DImentioning

confidence: 99%

“…The S parameters can be exported as Touchstone 2-port files and imported directly into the 3D Smith chart application. The application presents a visualisation of the 3D Smith Chart and a wide range of parameters useful in design and analysis, as described in [21][22]. The application is developed using the Java programming language and for the 3D rendering and interaction with the Riemann sphere the Open Graphics Library (OpenGL) Application Programming Interface (API) is employed.…”

Section: Applications In Reconfigurable Inductors With Vanadium DImentioning

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 2-port inductors [22], one may get the Q-frequency dependency directly from the S11reflection coefficient parameter, thus avoiding classical 2D Qfrequency plots previously employed by us [22][23] or other authors [24][25], in these type of evaluations. The proposed visualization on the 3D Smith chart proves its effectiveness for passive circuits, especially when Qs 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 Q evaluations. Here we test the temperature dependence of Q for fabricated inductors with VO2 by sweeping it from 25°C to 50°C -directly from the vector network analyser with the newly developed technique.…”

Section: Introductionmentioning

confidence: 97%

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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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Section: B 3d Smith Chart Representation Of Constant Q Semicirclesmentioning

confidence: 99%

Section: Applications In Reconfigurable Inductors With Vanadium DImentioning

confidence: 99%

Section: Applications In Reconfigurable Inductors With Vanadium DImentioning

confidence: 99%

Section: Applications In Reconfigurable Inductors With Vanadium DImentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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

et al. 2020

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Radio-Frequency Characteristics of Ge-Doped Vanadium Dioxide Thin Films with Increased Transition Temperature

Müller

Khadar

Abel

et al. 2020

ACS Appl. Electron. Mater.

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This work investigates and reports on the radio-frequency (rf) behavior in the frequency range of 5–35 GHz of germanium-doped vanadium dioxide (Ge-doped VO2) thin films deposited on silicon substrates via sputtering and pulsed laser deposition (PLD) with estimated Ge concentrations of 5 and 5.5%. Both films exhibit critical transition temperatures (T c) of 76.2 and 72 °C, respectively, which are higher compared to that of the undoped VO2 which undergoes reversible insulator-to-metal phase transition at 68 °C. Both types of Ge-doped films show low hysteresis (<5 °C) in their conductivity versus temperature characteristics and preserve high off-state dc-conductivities (corresponding to the insulating state of the phase change material) of 13 S/m for the sputtered and 55 S/m for the PLD-deposited film, respectively. The dc on-state (corresponding to the conductive state of the phase change material) conductivity reaches 145,000 S/m in the case of the PLD film, which represents a significant increase compared to the state-of-the art values measured for undoped VO2 thin films deposited on identical substrates. In order to further understand the off-state dissimilarities and rf behavior of the deposited Ge-doped VO2 films, we propose an original methodology for the experimental extraction of the dielectric constant (εr) in the GHz range of the films below 60 °C. This is achieved by exploiting the frequency shift of resonant filters. For this purpose, we have fabricated coplanar waveguide structures incorporating ultracompact Peano space-filling curves, each resonating at a different frequency between 5 and 35 GHz on two types of substrates, one with the Ge-doped VO2 thin films and another one using only SiO2 to serve as the reference. The reported results and analysis contribute to the advancement of the field of metal–insulator–transition-material technology with high T c for rf industrial applications.

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Temperature dependence of reconfigurable bandstop filters using vanadium dioxide switches

Müller

Cavalieri

Ionescu

2020

Applied Physics Letters

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In this letter we report and investigate the temperature dependency of various radio frequency parameters (RF) for a fabricated reconfigurable bandstop filter with vanadium dioxide (VO2) switches measured up to 55 GHz. Here the insulator to metal (ITM) and metal to insulator transition (MIT) hysteresis of the VO2 thin film influence on the RF characteristics of the filters is analyzed from 25 °C and 120 °C in heating and cooling.The resonance frequency and maximum insertion loss (IL) stability and sensitivity with temperature variations are explored. It is noticed that increasing the temperature with 50 °C from 25 °C (or decreasing it with 50 °C from 120 °C) will result in a less than 1% fractional frequency shift in respect to the off and on resonance frequencies. The sharp DC conductivity levels variations of the VO2 thin film around the transition temperatures translate into sharp effects on the resonance characteristics of the filters. On the contrary, the maximum IL levels are less sensitive to the DC films sharp conductivity changes around the VO2 transition temperature. Last, we see that the RF parameters in heating and cooling at 80 °C, above (but close to) the DC transition temperatures of VO2 exhibit completely different resonance frequencies. The RF results reported close to the transition temperatures for the VO2 thin films can diverge in heating and cooling, thus of a more insightful understanding of VO2 reconfigurable RF devices has to include 2 temperature dependent measurements at various temperatures below MIT and ITM in the RF ranges too.

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

Cited by 6 publications

References 48 publications

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

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

Radio-Frequency Characteristics of Ge-Doped Vanadium Dioxide Thin Films with Increased Transition Temperature

Temperature dependence of reconfigurable bandstop filters using vanadium dioxide switches

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