Spiral Inductor

The 3rd Dimension: This inductive, mostly planar structure contains an air bridge. Therefore the third dimension has to be taken into consideration and common replacement circuit models are not sufficient anymore. A real 3D field solution is required. T. Becks and I. Wolff discussed this structure in: "Analysis of 3-D metallization structure by a full-wave spectral domain technique," IEEE Trans. on Microwave Theory and Tech., Vol. MTT-40, Dec. 1992, PP. 2219-2227.

Here results of CST MICROWAVE STUDIO® (CST MWS) simulations are presented and compared to the published results.

Figure 1: Structure plot of the spiral inductor

The width of the microstrip line (blue material) amounts to 0.625 mm. In the center the air bridge is visible (thickness 5 microns). The red material represents alumina substrate with a permittivity of 9.8.

Figure 2: Comparison of CST MWS simulation and measurement results

Amplitude of S11 (linear): The CST MWS simulation (red line) shows a good agreement with the calculation presented by Becks and Wolff (black line). Frequency range: 7 to 14.5 GHz. Black dashed line: measurement.

Figure 3: Current distribution on the microstrip lines for 12 GHz

Figure 4: Smith Chart for the frequency range 7 to 14.5 GHz

CST Article "Spiral Inductor"
last modified 4. Jul 2008 3:35
printed 4. Jul 2008 3:35, Article ID 39
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Article ID: 39 Last modified: 4. Jul 2008 3:35

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