Stackup Editing (Cont.)

Notes:

The Stackup Editor, available under Stackup on the main toolbar or as an icon, can be used to modify the stackup to improve signal integrity. You add (and delete) layers and modify both dielectric and metal layer characteristics to correspond to your manufacturing requirements. You can also assign colors to each layer; these colors are used when displaying traces. Also, the stackup view can be saved to a Microsoft-compatible clipboard.

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HyperLynx Signal Integrity Analysis 5-5

Notes:

The impedances values shown in the stackup window are calculated for the Test Trace Width shown in the Edit Layer window. Actual values in the schematic will depend on the actual trace width. Width compensation factors, which account for variations in fabrication during and plating, can be set in Preferences under

Options; compensation is applied before impedances are calculated. The layer can also be changed to another layer type in this window. The

Advanced option allows you to set bulk resistivity and temperature coefficient for the metal layers.

Similarly, the Edit Layer window for dielectrics allows you to set the dielectric constant and the thickness. One use for this is examining the effects of fabrication

Stackup Editing (Cont.)

HyperLynx Signal Integrity Analysis 5-6

Running LineSim

variations in dielectric constant, which depends on both material and fabrication (for example, FR-4 can vary between 4.3 and 4.9 due to the curing process). The layer can also be changed to another layer type in this window.

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HyperLynx Signal Integrity Analysis 5-7

Stackup Editing (Cont.)

Notes:

The Stackup Wizard, under Wizards on the main toolbar, can be used to check your stackup. The Stackup Wizard will report errors that cannot be corrected. The examples shown here include one stackup with no errors and one where there is no dielectric between two metal layers. While the Stackup Wizard will try to clean up any problems that it finds, you should fix the stackup to make sure the correct information is used.

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Running LineSim

Stackup Editing (Cont.)

Notes:

To add an IC pin, left click on any gray IC pin symbol in the schematic. To assign a model to this pin, put the cursor over the pin and right click on the same pin to open the Model selection window. The Assign IC Models window opens.

Stackup Editing (Cont.)

♦ Left click to add/delete pin

♦ Cursor marks selected component

♦ Component also highlighted

♦ Right click to open the Assign Models dialog box

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HyperLynx Signal Integrity Analysis 5-9

Stackup Editing (Cont.)

Notes:

There are about 8,000 models available to choose from, including IBIS models as well as models for ferrite beads, PML (packaged generic parts) and MOD

(technology models) in HyperLynx's proprietary model formats. To select a model, left click on Select in the Assign IC Models window, which opens the Select IC Model window. Left click on the radio button to select the library of parts you wish to use, and then select the model by left clicking on the device name and then the pin name. Note that there may be more than one component within a single file, as shown here. After selecting a model, click OK. The Select IC Model window will close, and the Assign IC Models box will now show the model you selected.

HyperLynx Signal Integrity Analysis 5-10

Running LineSim

Stackup Editing (Cont.)

Notes:

When the Select IC Model window closes, the power supply voltage is checked. If the voltage is different for this pin than for the current voltage set for the simulator, you will be asked if you wish to update the voltage for simulation. An IC buffer model may be an input, output, or bi-directional I/O. Once you have selected a model, you can select from the I/O options by left clicking the

appropriate radio button in the Buffer Settings area of the Assign IC Models window.

When you open the Select IC Model window, you can assign as many models as you want to the pins. To assign the same model to several pins, you can use the

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HyperLynx Signal Integrity Analysis 5-11

Copy and Paste buttons. It is often convenient to assign the models using copy and paste, and then to assign the input and output directions.

Under File, there is an option to generate a model finder index, which updates HyperLynxIcModels.CSV in the HyperLynx install directory. The Find Model option on the Select IC Model window then allows you to locate models using keyword searches in this file.

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Running LineSim

Stackup Editing (Cont.)

Notes:

To add a transmission line, left click on any gray transmission line symbol in the schematic. To assign a model, put the cursor over the transmission line and right click. The Edit Transmission Line window opens. You can use the radio buttons to select the type of transmission line (including connectors and cables). The area on the right side of the window displays the properties of the current transmission line. You may use the "Comment" text box to label your transmission line.

When you select any type of transmission line, there will be a place to enter the characteristics (usually under the Values tab). The characteristics that can be entered depend on the type of transmission line selected. For example, for a cable, you can choose from a pick list of standard cables, while for a stackup you can

Stackup Editing (Cont.)

♦ Left click to add/delete transmission line

♦ Left click also makes an “ideal” wire

♦ Cursor marks selected component

♦ Component also highlighted

♦ Right click for transmission line type

♦ Radio button selects type

♦ Enter text comment

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HyperLynx Signal Integrity Analysis 5-13

specify layer, length, and width. You can use Copy to use the same characteristics for additional transmission line segments.

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Running LineSim

Stackup Editing (Cont.)

Notes:

When you select the Values tab, the Values for the currently selected transmission line type can be entered into the text boxes or selected from a pulldown list. The electrical properties are calculated and displayed.

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HyperLynx Signal Integrity Analysis 5-15

Stackup Editing (Cont.)

Notes:

Coupled transmission lines require that the coupled lines all be of type Stackup. This is because the crosstalk simulation uses information from the stackup to obtain the field coupling. Coupled lines must be in the same row (or column) to be coupled; if they are in different row or columns, they will automatically be assigned to different coupling regions.

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Stackup Editing (Cont.)

Notes:

Once a transmission line has been assigned a type of Coupled Stackup, a new set of tabs is available in the Edit Transmission Line window. First, the transmission line is assigned to a coupling region using Add to Coupling Region. Once the coupling region has been assigned, the tab name changes to Move to Coupling Region, allowing you to move the transmission line to a different coupling region at any time. The Edit Coupling Region tab allows you to assign length, spacing, and layers to all traces in the coupling region.

The field solver tab allows you to view the electric field lines and propagation characteristics of each mode for the selected coupling region. Note that the field solver view can be copied to the Microsoft-compatible clipboard.

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Stackup Editing (Cont.)

Notes:

Passive components have both values and parasitics that can be set within

LineSim. The parasitics will depend on both the packaging and the connection to the board (through-hole having higher inductance than surface mount, for

example). In addition, a via can be modeled by setting the resistor value to zero and setting the parasitics to values typical for your vias.

A series component can be removed by setting its type to None. AC components can be removed by left clicking on the component symbol.

Stackup Editing (Cont.)

♦ Parallel Passives: Left click to add or delete

♦ Series passives: Left click,then select the type from menu (None to

remove it)

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Running LineSim

In document HyperLynx Signal Integrity Analysis Student Workbook (Page 154-168)