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2 Two-layer Edge (Protective Layer/Substrate) Coupled Microstrip Lines (EM Quasi-Static): MM2CLIN

Symbol

Summary

MM2CLIN models section of two edge coupled microstrip lines placed on the upper surface of a two-layered substrate. Lower layer of the substrate may have conductive loss.

Topology

Parameters

Name Description Unit Type Default
ID Element ID Text TL1
W1 Width of conductor 1 Length W[1]
W2 Width of conductor 2 Length W[1]
S Spacing between conductors Length L[1]
L Conductor length Length L[1]
Acc Accuracy parameter   1
MSUB2 Substrate definition Text MSUB[2]

[1] User-modifiable default. Modify by editing under $DEFAULT_VALUES in the default.lpf file in the root installation directory. See the AWR Microwave Office Layout Guide for details.

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

Parameter Details

Acc. The parameter Acc is the accuracy parameter. The default value for Acc is 1. If Acc is less than 1 or greater than 10 it is set automatically to 2.

Parameter Restrictions and Recommendations

  1. Accuracy parameter A is limited to 1≤Acc≤10. Larger value of Acc increases density of mesh used in computations. Accuracy of model parameters may gain slightly from increasing Acc at the expense of noticeable growth of computation time. As a rule of thumb, good trade-off between accuracy and computation time is to set Acc to 1.

  2. This component does not impose restrictions on the conductor thickness (thickness may be zero, positive, or negative). Negative thickness means that the conductor is recessed into the substrate.

  3. Substrate parameters Tand1, Tand2 (loss tangents for upper and lower layers) should not exceed 3.0; substrate parameter Sig2 (bulk conductance of the lower layer) shouldn't exceed 3 S/m.

Implementation Details

Model implementation is based on EM Quasi-Static technique described in [1]. It accounts for losses in metal and in substrate dielectrics. Polarization loss (Tand1,Tand2) are allowed in both substrate layers. Conductive loss is allowed in lower layer only. Dispersion is partly included.

Layout

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.

Recommendations for Use

This element may be used to model microstrip line over semiconductor substrate insulated with oxide or another semiconductor. For example, MM2LIN may model microstrip line on SiO2/Si substrate or on GaAs/Si substrate. However, this model imposes limitations on the allowed level of polarization and conductive losses, for instance, only high resistance silicon (HRS) substrates may be modeled.

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.

If thickness of any layer is too small in comparison with the thickness of another layer, simulation time may also noticeably grow.

References

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.

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