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Rectangular Microstrip Inductor Strip Bridge (EM Quasi-Static): MRINDSBR



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



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
AB Angle of bridge departure Angle 0 deg
W Conductor width Length 10 um
S Conductor spacing Length 5 um
WB Width of bridge strip conductor Length 10 um
HB Height of bridge dielectric Length 2 um
LB Length of bridge extension beyond inductor Length 0 um
EPSB Relative dielectric constant of bridge dielectric   1
TDB Loss tangent of bridge dielectric   0
TB Thickness of bridge strip Length 1 um
RhoB Bridge metal bulk resistivity normalized to gold   1
MSUB Substrate definition Text MSUB1[1]

[1] Modify only if 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+WB)/2. If you define too small a value of LN, the model automatically sets LN to (W+WB)/2 and issues a warning.

AB. Angle AB (degrees) defines the direction of bridge departure from the end of the last segment. Only 0, 90, 180 and 270 are allowed for AB. A zero angle has a bridge that is parallel to L1 and goes to the opposite direction. Angle is measured counterclockwise. Any intermediate value of AB is set to the closest acceptable value.

Bridge is not allowed to overlap the last segment. If this occurs, the model changes AB so that the bridge departs in the opposite direction (this is made only for evaluation of capacitance coupling between bridge and inductor segments).

NOTE: The layout cell does not reflect a change in bridge orientation in version 5.53 and earlier versions. Starting with version 6.53, a new version of layout cell overrides the setting for AB and sets the bridge exit to the opposite direction if overlapping occurs. By default, projects created in version 5.53 and earlier versions use the old version of the layout cell. Projects created in 6.53 and later use the new layout cell by default. You can update the layout cell assigned to this model. To do so, double-click the model symbol in the Schematic window to open the Element Options dialog box for the model, click the Layout tab and select either MRINDSBR2 as a new layout cell or MRINDSBR as the old layout cell.

Out90deg (Layout cell parameter only): Note that the layout cell for this model has parameter a Out90deg parameter (to edit values of this parameter select the corresponding layout cell, right-click and choose Shape Properties). On the Parameters tab of the dialog box that displays, setting this parameter to nonzero means that the orientation of a face at port 2 provides a connection to an external circuit via right (90deg) bend. Correspondingly, setting this parameter to zero means that the orientation of a face at port 2 provides an "in line" (no bend) connection to external circuit. The default value is zero. Setting this to a nonzero value (for example, to 1) does not effect the electrical properties of the model; no bend component is added automatically. You can attach any bend model to the port 2 if needed.

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).

Implementation Details

To decrease the calculation time for schematics that contain several MRINDSBR inductors, cache is implemented for this model. This means that during the first evaluation of the schematic the most time-consuming intermediate parameters for each inductor instance are being 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 the 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, the time saving due to caching may be relatively moderate.

Caution: 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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