Tools Menu

ICEM model expert

The ICEM model expert helps to generate a simple R,L,C model of an integrated circuit, with the supply model and internal current generator model, based on technological and switching parameters. The objective of the ICEM model (Integrated Circuit Electrical Model) for Components is to propose electrical modeling for integrated circuit internal activities. This standard model (IEC 62014-3) will be used to evaluate electromagnetic behavior and performances of electronic equipments.

The resulting schematic diagram is automatically generated from the parameters given in the following menu.

Advanced SPICE and IBIS

The Advanced SPICE and IBIS tool uses IBIS file information to:

• Generate a physical symbol including the pin list and package shape
• Evaluate the R,L,C values for each pin of the package and mutual couplings. The evaluation is based on physical estimation of the package lead length and bonding length (R,L,C distribution)
• Generate advanced IBIS netlist including accurate evaluations of packge and lead elements (IBIS netlist)
• Generate sub-circuit containing all R,L,C sub-elements in a Spice-compatible format (Spice Netlist)

The tool can be opened by clicking Tools -> Advanced SPICE and IBIS or from the IBIS editor interface. When the tool is launched, the IBIS data have to be loaded (File -> Load IBIS). The following figure presents the interface of the tool Advanced SPICE and IBIS. The left part of the screen helps user to select the elements to add in IBIS file (parasitic R, L, C, complex description of package, inductance, capacitance matrix...) and generate SPICE subcircuit from IBIS information. I nthe right part, several windows are proposed to:

• Edit and modify some special keywords added in IBIS file to describe the package geometry
• Display the updated IBIS netlist depending on the complexity level chosen by user
• Display the SPICE netlist generated from package information
• Display the R,L,C of the pins of the package
• Display the mutual couplings (capacitive and inductive couplings) between the pins of the package.

PWL Souce Generator

The Piece-Wise-Linear source generator is a convenient way to build an arbitrary input waveform as a voltage source for simulation. A powerful mathematical set of routines enable to describe virtually any waveform and tranform it into a series of (Time,Voltage) points. Predefined waveform descriptions are proposed in the upper menu, based on a reduced set of parameters that are listed on the right side. The user can manually edit the equation in order to obtain his own waveform. The output of this tool is a text file that is compatible with SPICE PWL source description.

An example of output TXT file ("PWL.TXT" by default) is given below:

* PWL description for 1.0000*exp(-t*/0.15e-9)-exp(-t*/100.0000e-9)
+(0.0NS 0.0000 1.0NS -0.9888 2.0NS -0.9802 3.0NS -0.9704 4.0NS -0.9608 5.0NS -0.9512 6.0NS -0.9418 7.0NS -0.9324 8.0NS -0.9231
+9.0NS -0.9139 10.0NS -0.9048 11.0NS -0.8958 12.0NS -0.8869 13.0NS -0.8781 14.0NS -0.8694 15.0NS -0.8607 16.0NS -0.8521
...

LC Resonant Frequency

The "Resonant Frequency" tool included in IC-EMC computes the impedance of L, C at a given frequency. The LC resonance is also computed, with its associated characteristic impedance.

dB/Linear unit converter

The dB and unit converter window helps computing the correspondence between linear and dB units. The value in V can be converted into dB. A value in dB may be converted into linear scale. Available units are V, A and Watts. For Watts, the log scale is 10.log(Y), and 20.log(x) for the other units.

Interconnect Parameters

The "Tools à Interconnect parameters" tool included in the Tool menu computes the R,L,C parameters of an interconnect based on its physical dimensions. Analytical formulations are used for these evaluations.

The "Interconnect parameters" tool included in IC-EMC computes the R,L,C parameters, the characteristic impedance, the propagation delay and the dielectric losses of an interconnect based on its physical dimensions. Different analytical formulations and numeric computations are used to extract these data (see IC-EMC User Manual for more information about the used formulations). In IC-EMC version 2.5, the following line configurations are implemented:

• Microstrip line
• Centered stripline
• Buried microstrip line
• Edge coupled microstrip lines
• Edge coupled stripline
• Loop antenna
• Via
• Coplanar waveguide
• Grounded coplanar waveguide
• N parallel lines

First, select the interconnect types by choosing the adequate cross section. Enter the information about geometry and materials of the interconnect. Then, click on “Apply y=f(x)” to apply analytical formulations to compute the different electrical parameters of the interconnect (resistance, capacitance, inductance per unit length, characteristic impedance, skin effect, propagation delay, loss). Finally, an SPICE equivalent model of the interconnect made of RLC cells can be automatically built. Enter the limit frequency of validity of the model (field “Freq (GHz)”) and click on the button “SPICE Model”. Automatically, the equivalent SPICE schematic is displayed on the main screen of IC-EMC. You can also give geometrical coordinates to inductances of interconnects to perform near field emission simulations, by selecting the option “Near Field Analysis”.

Frequency / Wavelength Converter

The wavelength corresponding to a given frequency may be computed in a dedicated screen added to the EMC menu and called “Freq./Wavelength converter”. The formulation used for conversion is lambda= c/f.sqrt(epsr) with c=speed of light, f=frequency and epsr is the relative permittivity (1 by default).

Frequency Planning

When non linear devices are excited by several signals, the distorsion of these signals induced by the device behaviour leads to new harmonic content due to intermodulation products. The command “Tools à Frequency Planning” offers a simple calculator of frequencies of the new harmonics produced by the intermodulation products between two harmonic excitation signals F1 and F2. These new harmonics are characterized by two integer numbers (m,n) related the order of the intermodulation product, such that their frequency Fmn is given by:

The frequencies of both input signal are given in MHz, the maximum order for m and n is given in the field Max. Harmonic Index”, which is limited to 100. Click on the button Compute to extract the intermodulation product frequencies. The results are displayed in two tables: The “Frequency Planning Array” (on the left) gives the intermodulation product frequency value versus (m,n) couple. The “List of Frequency” (on the right) gives a list of all the new harmonic frequencies in ascending order. Click on the button Save to write both tables in an output file *.txt.

Patch Antenna

The “patch” is a low gain, narrow-bandwidth antenna. Many types of vehicles concerned with aerodynamic considerations require such type of low-profile antennas. Typically, a patch consists of a thin conducting sheet mounted on a substrate and isolated by a dielectric. The patch-to-ground-plane spacing is usually around l/100. The patch length is designed based on the desired resonance with W=l, while L is often constrained by availability of space in the electronic device. A practical choice of L is l/2. A larger L would increase efficiency but higher order modes might distort the radiation patter.

In susceptibility analysis, the IC may be considered as a resonant system in very high frequency. The screen “Patch Resonant Frequency” computes the resonant frequencies according to simple patch antenna formulation linked to the patch physical dimensions. More details are given in the software appendix.

Attenuation in cables

The command “Tools -> Attenuation in cables” helps the user to estimate the attenuation brought by bifilar and coaxial cables, which constitutes the most common cables used for EMC. This tool is similar to Interconnect Parameters, but it is only dedicated to cables.

The figure below presents the user interface of the tool Geometrical parameters as inner/outer diameter and length for coaxial cables, and wire diameter, separation and length for bifilar cables, and physical parameters given by cable providers such as dielectric constant, metal conductivity, loss tangent of dielectric materials, and frequency to compute the following electrical parameters:

• Capacitance and inductance per unit length
• Characteristic impedance
• Loss per unit length (dB/m)and total loss (dB)

Spectrogram

The command "Tools -> Spectrogram" gives access to display of the energy content of a signal (using a palette of colors) versus frequency (Y axis) and versus time (X axis). The spectrogram is obtained by computing several FFT and shifting the FFT window until the whole signal is covered. The FFT is applied iteratively on a reduced number of points, and then shifted and X and Y axis may be modified using the icons situated on the top-left corner of the screen. This analysis is very similar to the FFT done in the Emission interface, but it offers the possibility to follow the evolution of the emission versus time, for example when the simulated circuit alternates several long cycles.

The following screen described the spectrogram interface. This tool is also available from the "EMC --> Emission dBµV vs Frequency". Load a SPICE transient simulation in the field SPICE simu, select a maximum frequency and a number of point for FFT analysis (FFT resolution). The button Plat sound offers an original way to analyze the spectral content of the electromagnetic response of a circuit. The transient signal is converted into a WAV sound and executes it on the windows mediaplayer. The high frequency content (in the MHz - GHz range) is brought in the audible range.

3D package viewer

The package viewer is based on IBIS information of the integrated circuit. Use the command “Tools à 3D-Package Viewer” to display the 3D aspect of the package, including the IOs, IC location and lead-frame structure. When the 3D-package viewer is launched, the tool asks for a IBIS file.

The figure below presents the 3D package viewer. Use the X, Y, Z to move the viewer’s position in 3D and the light position cursor to change the rendering. The package color and the IC colors are user accessible. The “Demo” button displays the IC in 3D with varying observation angles. The color code for pins is as follows:

• Supply balls are in red (VDD, VCC)
• Ground balls are in blue (GND, VSS)
• I/O balls are in yellow
• Non-connected balls are in Gray

Check floating lines

The command "Tools -> Check Floating Lines" can detect problems of interconnections in the schematic. The schematic diagram is scanned in order to detect interconnects with a wrong connection to the symbol or other interconnects, as shown in the figure below. An indication points the floating line until a line is added.

Convert BGA matrix to IBIS file

This command is used to generate an IBIS file from the BGA pin list.

Advanced package model

The command “Tools -> Advanced Packaged Model” opens a tool that helps to automatically generate realistic model of package and compute electrical parasitic elements (R, L, C). The tool proposes several types of packages: Dual In Line, Small Outline Package, Quad Flat Package and Ball Grid Array. While the 3 first package type models are automatically built, the last one is manually reconstructed by the user with a special interface.

The figure below presents the user interface, which is composed of three tabs:

• Package generation, from a predefined package type and a set of geometrical information. At the beginning, only this tab is opened. Click on Generate GEO Model to construct the model and generate a .geo file, that contains the geometrical description of the package. Then the two other tab appear. If BGA is selected, a new interface opens to help the user to create manually the geometrical model. On the left part of the screen, an existing .geo file can be imported (Import Geo Model).

• Model viewer, to verify the validity of the generated package model.

• Compute parasitic, to extract resistances, partial inductances and capacitances of each pins of the package with mutual couplings by a Partial Element Equivalent Circuit. More details can be found in the ICEMC User Manual. Set the frequency, the conductivity of metal material and dielectric constant of the package material. Then select the electrical elements that you want to compute (R, L, or C). Click on Compute to launch the numerical computations. Each leads are meshed and PEEC method is applied. The simulation process depends on the number of lead, the advancement of the simulation is indicated by a progression bar. The results of the simulation are written in *.R, *.L and *.C files. Finally, choose the electrical element that you want to display (resistance, self inductance or capacitance, mutual inductance or capacitance) and click on Add. The values of selected parameter for each pin are displayed, as shown below. The min, typ, max value for self inductance and capacitance, and serial resistance of package pins are summed up in the table Results.

S parameter deembeding

The command "Tools à S Parameter Deembedding" proposes a tool dedicated to the deembedding of S11 parameter measurements. Deembedding a S11 parameter measurement means removing the influence of parasitic attachments (coaxial cables, microstrip lines …) used to connect the device under test input to the calibration plane of a vector network analyzer. See the IC-EMC User Manual for more information about S parameter deembedding. The raw S11 measurement can be provided by a file in .s50 or Touchstone .s1p format, the deembedded S11 can be exported in a .S50, .Z or Touchstone .s1p format. Note that the tool "EMC -> S parameters" allows S parameters to be exported in a Touchstone format.

The following figure describes the interface of the tool. The left part is dedicated to the import of input file used in the deembeding process, display configuration and export deembedding results, while the right part displays the raw S11 measurement and the deembedded S11, in a S or Z parameter form. First, select a raw measurement to deembed and click Load. The measurement is displayed in the graph. Two cases are considered in the deembedding process and are linked to the two tabs in the left part of the screen. If a matched line connects the measurement system, i.e. the calibration plane, to the device under test, select Matched Line and set the delay of the line. If a more complex line connects the measurement system to the device under test, the complete full two port characterization of this line is required. Then, select Unmatched Line tab and choose the Touchstone file .s2p, which provides a two port S parameter characterization of the line. The deembedded S11 is automatically computed and displayed in the graph.

Eye Diagram

The command “Tools à Eye diagram” opens a special screen for plotting eye diagram for signal integrity analysis. The tool must be launched only if a schematic containing an Eye Diagram symbol (available in ieee\EyeDiag.sym, then click on Insert à User symbol (.SYM)) have been loaded on IC-EMC interface and the associated SPICE simulation result file exist. In these conditions, when the eye diagram tool is launched, the SPICE simulation result file name (*.txt) appears in the field “Simulation Data Source”. Click on the button Eye to plot the eye diagram. With a left click and a drag of the mouse, the horizontal or vertical aperture of the eye can be measured.

Only one eye diagram symbol is supported by schematic. All voltage or current probes should be desactivated for eye diagram simulation.

Cavity Model

The tool “Tools à Cavity Model” is dedicated to the simulation of Z matrix between several ports placed on a rectangular cavity formed by a power and ground plane pair. The model relies on an analytical cavity resonator model. The analytical method is based on the solution of Helmholtz equation with the Green’s function for rectangular plane. The following figure presents the default screen dedicated for power and ground planes dimension and property configuration. The power and ground planes lies on (x,y) plane and are separated by the distance “Thickness”. In the table Access Point, the (x,y) coordinates of the input ports are defined. The port shape is assumed square and their width is given in the column “W (mm)”. Click on “Add access” to add a new port, or “Remove access” to remove the last defined port. The analytical computation is configured in the screen called “Model Parameters”. The maximum cavity resonance orders and the frequency sweeping configuration are defined here. Click on the button Compute Model to launch the analytical simulation. Finally, the results can be plotted on the graph on the right part of the screen, from the screen “Results” (next figure). The Z parameter of the N port matrix can be plotted versus the frequency. The total inductance and capacitance of the power plane are also computed. The Z matrix can be saved in an output file in Touchstone format.

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