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

Victor Asavei,Esther Sanabria-Codesal,Alin Moldoveanu,Andrei A Muller,Adrian M Ionescu

doi:10.1109/access.2020.3026917

Victor Asavei, Esther Sanabria-Codesal + Show 3 more

Open Access

https://doi.org/10.1109/access.2020.3026917

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Abstract

The article proves first 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 semi-circles families in the north hemisphere while represented on a 3D Smith chart. On the contrary we show 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. Also, we find out that these constant Q contours represent complementary semi-circles in the south hemisphere while represented on the 3D Smith chart for negative resistance circuits. The constant Q - computer aided design (CAD) implementation of the Q semi-circles on the 3D Smith chart is then successfully used to evaluate the quality factor variations of newly fabricated Vanadium dioxide inductors first, directly from their reflection coefficient, as the temperature is increased from room temperature to 50 degrees Celsius ({\deg}C). Thus, a direct multi-parameter frequency dependent analysis is proposed including Q, inductance and reflection coefficient for inductors. Then, quality factor direct analysis is used for two tunnel diode small signal equivalent circuits analysis, allowing for the first time the Q and input impedance direct analysis on Smith chart representation of a circuit, including negative resistance

Highlights

The Smith chart [1], [2], which, was invented by Philip Hagar Smith in 1939, has survived the passing of years, becoming an icon of microwave engineering [3]
Asavei et al.: 3D Smith Chart Constant Quality Factor Semi-Circles Contours for Positive and Negative Resistance Circuits for negative resistance circuits, we prove that these represent semi-circles in the South hemisphere
In order to prove the utility of our computer aided design (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 S11-reflection coefficient parameter, avoiding classical 2D Q-frequency plots previously employed by us [22], [23] or other authors [24], [25], in these type of evaluations

Summary

Introduction

The Smith chart [1], [2], which, was invented by Philip Hagar Smith in 1939, has survived the passing of years, becoming an icon of microwave engineering [3]. Displaying the 1-port reflection coefficient (grounding the second port), we can directly detect the quality factors and while using the 3D Smith chart implementation, visualize the extracted inductance and frequency dependency in a concomitant view.

Results

Conclusion