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    Publication
    Compact Modeling of Proximity Effect in High- Q Tapered Spiral Inductors
    (01-04-2018)
    Sathyasree, J.
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    Vanukuru, Venkata
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    Nair, Deleep
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    This letter presents a technique to accurately predict the proximity effect losses in spiral inductors with variable width and spacing (taper) across the turns. The change in magnetic flux in a spiral turn due to the nearby non-uniformly spaced traces is considered while developing expression that captures proximity effect. A broadband, scalable, and frequency-independent compact model is developed for tapered inductors using the proposed technique. Resistance, inductance, and quality factor plots are shown for spiral inductors with different values of taper. Excellent agreement between model and EM simulated/measured data demonstrates the scalability of the proposed model. The proposed model can be used to accurately predict the high possible with tapered inductors.
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    Publication
    A Substrate Model for On-Chip Tapered Spiral Inductors with Forward and Reverse Excitations
    (01-01-2019)
    Sathyasree, J.
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    Vanukuru, Venkata
    ;
    Nair, Deleep R.
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    In this brief, closed-form analytical expressions are obtained to accurately calculate the oxide and substrate (both lateral/vertical) capacitances of the π-equivalent circuit model for on-chip tapered spiral inductors. A lateral RC substrate network using the above-mentioned expressions is shown to significantly improve the model accuracy, especially with lower substrate resistivities. Furthermore, improvement in Qmax with reverse excitation in tapered spirals is also accurately predicted by the proposed model. The accuracy of the proposed model is validated till 15 GHz using several inductor geometries across process parameters suitable for the design of RF circuits. Excellent agreement is observed between the model, electromagnetic simulations, and measurements.