Multilayer Substrate Analysis

Multilayer Substrate Analysis

The CONMLS code is a modern Fortran implementation of the models discussed in [1, 2, 3, 4, 5] to simulate multilayer substrates enclosed by solid reference planes. Example screenshots of the graphical user interface are given in Figures 1 and 2.


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Figure 1: Graphical user interface of the CONMLS code. The visualization of the geometry is split into a 2D bird’s view (central view) and the stackup (right-handed view).


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Figure 2: Scattering parameters of the crosstalk between two vias in a via pin field derived using CONMLS.

Figure 3 illustrates the program functionality and main building blocks. An interpreter reads the input files, which are a high-level description of the structure to be simulated. These files are then decoded. A second code component gets the variables created by the interpreter and identifies the cavities and their related interconnect elements. Then, the calculator computes the parallel-plate impedance per cavity, generates or imports the transmission line models for traces, and calculates or reads the via-to-plane capacitances to approximate the near fields in the antipad region. The calculator combines the plane and trace model by applying modal decomposition, and creates the interconnection matrices for via capacitances and lumped elements. Finally, the partial results are concatenated using, for instance, segmentation techniques. Post-processing functions and utilities are available to store (e.g. as lydite- or touchstoner files [6]) and visualize the results. This version utilizes a revised CIM package [7] which allows the computation of arbitrary-shaped planes by applying the contour integral method. Another previously external algorithm for the computation of MTL systems with an hybrid 2D approach for arbitrary cross sections [7, 8] is included in the CONMLS code.


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Figure 3: Flow chart of input/output and code functionalities in CONMLS.


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Figure 4: Input files for the high-level description of multilayer substrates in CONMLS are based on the widely used INI-format. Asterisks mark mandatory files. Other files may be required depending on the configuration of the algorithm.

Figure 4 shows the required input files and their dependencies. The fundamental configuration is provided through the simulation setup (.sim-file). The choice of algorithms and their respective parameters is contained in this file. Moreover, models may be freely parameterized with regard to variables and parameter sweeps, all of which are to be defined in the simulation setup. Additional files such as the geometry specification are linked. Geometry definition of PCB layout, stackup, vias, and multi-conductor transmission lines (MTLs) are to be provided through .geo-files. These files may utilize physical material definitions that are located in .matr-files.

Related Publications:

R. Rimolo-Donadio
Development, validation, and application of semi-analytical interconnect models for efficient modeling of multilayer substrates
Ph.D. dissertation, Hamburg University of Technology, Hamburg, Germany, 2010

R. Rimolo-Donadio, X. Gu, Y. Kwark, M. Ritter, B. Archambeault, F. de Paulis, Y. Zhang, J. Fan, H.-D. Brüns, and C. Schuster
Physics-based via and trace models for efficient link simulation on multilayer structures up to 40 GHz
IEEE Transactions on Microwave Theory and Techniques, vol. 57, no. 8, pp. 2072–2083, Aug. 2009

R. Rimolo-Donadio, A. Stepan, H.-D. Brüns, J. Drewniak, and C. Schuster
Simulation of via interconnects using physics-based models and microwave network parameters
Signal Propagation on Interconnects (SPI), 12th IEEE Workshop, May 2008

T. Reuschel, S. Müller, and C. Schuster
Segmented physics-based modeling of multilayer printed circuit boards using stripline ports
IEEE Transactions on Electromagnetic Compatibility, vol. 58, no. 1, pp. 197–206, Feb. 2016

T. Reuschel, M. Kotzev, D. Dahl, and C. Schuster
Modeling of differential striplines in segmented simulation of printed circuit board links
IEEE Int. Symp. Electromagn. Compat. (EMC), Ottawa, ON, Canada, Jul. 2016

EIA/IBIS Open Forum
Touchstone(R) (.SnP) file format specification. Rev 1.1
http://vhdl.org/ibis/connector/touchstone_spec11.pdf, Mar. 2014

X. Duan, R. Rimolo-Donadio, H.-D. Brüns, and C. Schuster
A combined method for fast analysis of signal propagation, ground noise, and radiated emission of multilayer printed circuit boards
IEEE Transactions on Electromagnetic Compatibility, vol. 52, no. 2, pp. 487–495, May 2010

H. Färber
Segmentierte Modellierung gekoppelter Mehrfachstreifenleitungen auf Leiterplatten
Bachelor Thesis, TUHH, 2011

S. Müller
Including multiconductor transmission lines in a quasi-analytical model for multilayer structures
Diplomarbeit, TUHH, 2009

Please find blow:

CONMLS is combined work according to the LGPLv3 conditions.

  • Qt source code download
  • Instruction for relinking to a modified version of Qt PDF
Bild LGPLv3

(Source Wikipedia)

CONMLS uses the HDF5 format for storing data.