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Round Bond Wire Over Substrate: WIRE1

Symbol

Summary

WIRE1 models a round bond wire connecting two conducting pads or microstrip lines. The model takes into account substrate proximity and the wire's arc shape

Structure

Parameters

Name Description Unit Type Default
ID Element ID Text TL1
L Wire length (distance between pads) Length L[1]
D Wire diameter Length W[1]
H Wire midpoint elevation over the substrate Length W[1]
Rho Metal resistivity relative to gold   1
MSUB Substrate definition Text MSUB1[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 the “Using Elements With Model Blocks” for details.

Parameter Details

H. The wire has an arc shape and H is the height of its summit point.

L. L is the shortest straight distance between points where wire is affixed to the pads

Implementation Details

This model is based on a quasi-static electromagnetic analysis described in [1]. It accounts for losses in metal and in substrate dielectric. Dispersion is partly included.

To decrease the calculation time for schematics that contain several of these elements, the electromagnetic analyses are cached; (saved and reused in later analyses). Thus, the first analysis of a circuit containing multiple bond wires takes longer than subsequent analyses.

NOTE: The quasi-static electromagnetic models use lengthy numerical algorithms which may lead to a noticeable increase in simulation time for schematics that employ many such models.

If wire elevation is very small in comparison with the substrate thickness, simulation time may also increase noticeably.

Layout

This element uses a special layout cell for a short circuit. The layout cell allows the elements connected on either side of the element to look through this element. For example, when a MLIN is hooked to a TFCM (capacitor) model and the project has bridge code configured, the line draws the proper interconnect between the line and the cap. If this element is placed between the line and the cap, the layout still draws the same.

You typically do not assign artwork cells to these items.

Recommendations for Use

For a wide range of substrate and wire parameters, the closed-form model WIRE2 may provide accuracy approaching that of WIRE1. However, the analysis of WIRE2 is based on an assumption that H is large relative to the substrate thickness, so WIRE2 issues a warning if the wire is placed too close to the substrate. WIRE1 may be useful for validation of designs using WIRE2.

References

[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.

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