Crosstalk

The Crosstalk calculation in the time domain allows you to calculate the crosstalk level (voltage) at the near and far ends of the transmission line, and display the crosstalk waveform in a line graph. This calculation type is available for single-ended transmission lines and differential pairs.

Examples

• Example - Evaluate Crosstalk-to-Signal Ratio
• Example - Calculate Trace Gap

Crosstalk Calculation Walkthrough

To perform a time-domain Crosstalk calculation, follow these steps:

1. Set the initial calculation settings:

   • Set Target to Transmission line
   • Set Target type to Single-ended or Diff pair
   • Set Mode to Time domain
   • Set Parameters to Crosstalk
   • Set Signal type to Digital or Analog

   

2. Select the required transmission line model and review it in the preview area.

   

3. Define the input parameters for the transmission line.

   

   Available parameters are listed below. Some of them may not be available for certain transmission line types.

   • H – Dielectric thickness. For each dielectric layer, you can specify its own thickness using the H1..H4 parameters (the number of H(n) parameters is determined by the number of dielectric layers).
   • Er – Dielectric constant. For each dielectric layer, you can specify its own dielectric constant using the Er1..Er4 parameters (the number of Er(n) parameters is determined by the number of dielectric layers).
   • W1 – Trace width.
   • W2 – Trace width after undercut.
   • T1 – Trace thickness.
   • C1 – Coating thickness.
   • CEr – Coating dielectric constant.
   • S1 – Diff-pair trace spacing (for differential lines).

   Parameters specific to Crosstalk calculations:

   • Transmission line count – 2 or 3.

   • V1, V3, V5... – The input voltage applied to Port 1, Port 3, Port 5, respectively. The total number of available voltage inputs corresponds directly to the number of transmission lines in the selected model.

     These parameters must be set to fixed values (Signal, or 0 V) using the drop-down menus. At least one port must be configured with a non-zero voltage, and at least one port must be set to zero.

   • LTL – Line length (mm).

   • G1 – Trace gap (mm).

   Digital signal parameters:

   

   • Y2 – Signal amplitude (V).
   • TR – Rise time (ns).
   • TF – Fall time (ns).
   • PW – Pulse width (ns).
   • PER – Period (ns).

   Analog signal parameters:

   

   • YAMPL – Signal amplitude (V).
   • PHASE – Signal phase (°).

4. Click Calculate in the lower-right corner of the calculation tab to run the calculation.

   

   Before running the calculation, you can click the dropdown arrow next to the Calculate button to choose between two calculation saving options:

   

   • Overwrite calculation – Saves the modified input parameters to the current calculation, overwriting previous data.
   • Save as new calculation – Saves the modified input parameters to a new calculation. This calculation will appear in the Projects panel.

Calculation Results for Single-Ended Lines

For single-ended transmission lines, the following parameters are calculated:

• Zo – Characteristic impedance (Ohm).
• U_NEXT – Near-end voltage (V).
• U_FEXT – Far-end voltage (V).

Use the settings in the Calculation results panel to customize the presentation of calculated parameters in table and graph formats.

Table Form

• U_NEXT checkbox – Specifies the visibility of the table with near-end voltage values.

• U_FEXT checkbox – Specifies the visibility of the table with far-end voltage values.

  

Graph Form

• Port setting — Allows you to select a port or multiple ports whose values are displayed in the graph.

  

Calculation Results for Differential Lines

For differential transmission lines, the following parameters are calculated:

• Zodd – Characteristic impedance of the line driven in odd mode (Ohm).
• U_NEXT – Near-end voltage (V).
• U_FEXT – Far-end voltage (V).

Use the settings in the Calculation results panel to customize the presentation of calculated parameters in table and graph formats.

Table Form

• U_NEXT checkbox – Specifies the visibility of the table with near-end voltage values.

• U_FEXT checkbox – Specifies the visibility of the table with far-end voltage values.

  

Graph Form

• Mode — Specifies display mode for the calculated crosstalk values. Available options include:

  • Odd mode
  • Even mode

  

• Port — Allows you to select a port or multiple ports whose values are displayed in the graph.

  

See Also

• Example - Evaluate Crosstalk-to-Signal Ratio
• Example - Calculate Trace Gap