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Rectangular Microstrip Inductor with Wire Bridge (EM Quasi-Static): MRINDWBR



This circuit component models a microstrip rectangular inductor with wire bridge at an internal port. MRINDWBR is based on an evaluation of self- and mutual-inductances, capacitances, and resistances between all parallel segments, which is based on an accurate quasi-static model of an arbitrary number of edge-coupled microstrip lines.



Wire bridge


Name Description Unit Type Default
ID Element ID Text MI1
NS Number of linear segments (>=4)   15
L1 Length of first segment Length 80 um
L2 Length of second segment Length 155 um
L3 Length of third segment Length 165 um
LN Length of last segment Length 35 um
W Conductor width Length 10 um
S Conductor spacing Length 5 um
LW Wire ridge length Length 500 um
DiaW Diameter of bridge wire Length 20 um
HW Wire bridge height Length 500 um
RhoW Bridge wire bulk resistivity normalized to gold   1
MSUB Substrate definition Text MSUB1[1]

[1] Modify only if the schematic contains multiple substrates. See “Using Elements With Model Blocks” for details.

Parameter Details

NS. The number of linear conductor segments forming the inductor. NS should be greater than 4 and less than NSMAX. The value of NSMAX can be evaluated from the condition LNMAX >0, where

LNMAX = L2-(NS-2)(W+S)/2 for even NS

LNMAX = L3-(NS-3)(W+S)/2 for odd NS

The layout feasibility check is run before performing calculations.

LN. The length of the last segment LN should not exceed LNMAX (see previous). If you define too large a value of LN, the model automatically sets LN to LNMAX and issues a warning. LN also should not be less than W/2. If you define too small a value of LN, the model automatically sets LN to W/2 and issues a warning.

LW. The distance between bridge wire attachment points (see Wire bridge in the "Topology" section). LW should be large enough to allow the bridge to reach an attachment point beyond the inductor boundary.

HW. The maximal height of the wire bridge above the substrate.

In90deg, Out90deg. (Layout cell): Note that the corresponding layout cell of this model has In90deg and Out90deg parameters (to edit these parameters, select the corresponding layout cell, right-click and choose Shape Properties to display the Cell Options dialog box). On the Parameters tab, setting these parameters to nonzero values means that the location of faces at the junction either at port 1 (In90deg) or at port 2 (Out90deg) provides connection to an external circuit via a right (90deg) bend. Correspondingly, setting these parameters to zero means that the location of the face at the corresponding junction provides an "in line" connection to an external circuit. The default values are zeros. Setting these to nonzero values (for example, to 1) does not affect the electrical properties of the model. No bend component is added automatically and you must attach the model of bend to the corresponding port at schematics.

Parameter Restrictions and Recommendations

  1. NS should be greater than 4 and less than NSMAX. The value of NSMAX can be evaluated from the condition LNMAX >0 (see previous).

  2. You should enter a sufficient value of LW to provide a bridge long enough to reach an attachment point beyond the inductor boundary.

Implementation Details

To decrease the calculation time for schematics that contain several MRINDWBR inductors, cache is implemented for this model. During the first evaluation of a schematic, the most time-consuming intermediate parameters for each inductor instance are stored in memory cache. Each inductor model checks this cache looking for its duplicate. Duplicate inductors copy the appropriate parameters from memory cache, saving substantially on their recalculation.

Note that this model caches only frequency-independent characteristics of coupled lines, but recalculates the large equivalent circuit network (derived from coupled line characteristics) at each swept frequency. Thus, if the number of swept frequency points is large (for example, 300) the total time spent on equivalent circuit evaluation may substantially exceed the time for evaluation of coupled line characteristics. In this case, time saving due to caching may be relatively moderate.

This model does not account for coupling between bridge wire and inductor segments. However, the wire bridge is substrate-aware, so the HW parameter may affect MRINDWBR performance.

NOTE: The implementation of EM Quasi-Static models relies heavily on the involved numerical algorithms. This may lead to a noticeable increase in simulation time for schematics that employ many such models.


This element uses line types to determine its layout. By default, the layout uses the first line type defined in your Layout Process File (LPF). You can change the element to use any of the line types configured in your process:

  1. Select the item in the layout.

  2. Right-click and choose Shape Properties to display the Cell Options dialog box.

  3. Click the Layout tab and select a Line Type.

  4. Click OK to use the new line type in the layout.

See “Cell Options Dialog Box: Layout Tab ” for Cell Options dialog box Layout tab details.

See “The Layout Process File (LPF)” for more information on editing Layout Process Files (LPFs) and to learn about adding or editing line types.


[1] M.B. Bazdar, A.R. Djordjevic, R.F. Harrington, and T.K. Sarkar, "Evaluation of quasi-static matrix parameters for multiconductor transmission lines using Galerkin's method," IEEE Trans. Microwave Theory Tech., vol. MTT-42, July 1994, pp. 1223-1228

[2] M. Kirschning, R.H. Jansen, N.H.L. Koster, "Measurement and computer-aided modeling of microstrip discontinuities by an improved resonator method," IEEE MTT-S International Microwave Symposium Digest, 1983, pp. 495-497.

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