High-speed signal routing basics in PCB Design - Real Business Scenario

Scenario Mode

👤 Your Role: You are a PCB design engineer working on a new high-speed communication device.

📋 Request: Your manager wants a report showing how signal integrity can be maintained by proper routing techniques in high-speed PCB design.

📊 Data: You have data on signal trace lengths, impedance values, and crosstalk measurements from recent PCB prototypes.

🎯 Deliverable: Create a dashboard that visualizes signal trace lengths, impedance control, and crosstalk levels to identify routing improvements.

Sample Data

Trace ID	Length (mm)	Impedance (Ohms)	Crosstalk (dB)	Layer
T1	45	50	-40	Top
T2	60	48	-35	Inner1
T3	30	52	-42	Top
T4	55	49	-38	Inner2
T5	70	50	-33	Top
T6	40	51	-41	Inner1
T7	65	47	-36	Top
T8	50	50	-39	Inner2

1

Step 1: Create a table visual showing Trace ID, Length, Impedance, Crosstalk, and Layer.

Add all columns from sample data as table columns in the BI tool.

Expected Result

A table listing all 8 traces with their length, impedance, crosstalk, and layer.

2

Step 2: Calculate average impedance per layer to check impedance control.

Use DAX measure: Average Impedance = AVERAGE('Table'[Impedance]) grouped by Layer.

Expected Result

Average impedance values: Top=49.75 Ohms, Inner1=49.5 Ohms, Inner2=49.5 Ohms.

3

Step 3: Create a bar chart showing average impedance by layer.

X-axis: Layer, Y-axis: Average Impedance measure.

Expected Result

Bar chart with three bars showing average impedance close to 50 Ohms for each layer.

4

Step 4: Calculate maximum crosstalk per layer to identify worst interference.

Use DAX measure: Max Crosstalk = MIN('Table'[Crosstalk]) grouped by Layer.

Expected Result

Max crosstalk values: Top=-33 dB, Inner1=-35 dB, Inner2=-38 dB.

5

Step 5: Create a line chart showing max crosstalk by layer.

X-axis: Layer, Y-axis: Max Crosstalk measure.

Expected Result

Line chart showing max crosstalk levels per layer, highlighting Top and Inner1 layers have highest crosstalk.

6

Step 6: Create a scatter plot of Trace Length vs Crosstalk to see if longer traces have more interference.

X-axis: Length (mm), Y-axis: Crosstalk (dB), Points labeled by Trace ID.

Expected Result

Scatter plot showing trend that longer traces tend to have higher (less negative) crosstalk values.

7

Step 7: Add slicer/filter for Layer to allow filtering visuals by PCB layer.

Add Layer column as slicer in the dashboard.

Expected Result

User can filter all visuals to show data for Top, Inner1, or Inner2 layers.

8

Step 8: Summarize findings in a text box on the dashboard.

Add text: 'Impedance is well controlled near 50 Ohms across layers. Crosstalk is highest on Top and Inner1 layers, especially on longer traces. Consider routing improvements on these layers to reduce interference.'

Expected Result

Dashboard includes clear summary of signal integrity insights.

Final Result

High-Speed Signal Routing Dashboard

+----------------+----------------+----------------+
| Layer Slicer   |                |                |
+----------------+----------------+----------------+
| Table of Traces | Bar Chart: Avg | Line Chart: Max|
| Trace ID, Length| Impedance by   | Crosstalk by   |
| Impedance,      | Layer          | Layer          |
| Crosstalk, Layer|                |                |
+----------------+----------------+----------------+

Scatter Plot: Trace Length vs Crosstalk

Summary Text Box:
"Impedance is well controlled near 50 Ohms across layers.
Crosstalk is highest on Top and Inner1 layers, especially on longer traces.
Consider routing improvements on these layers to reduce interference."

✓Impedance is consistently controlled around 50 Ohms on all PCB layers.

✓Top and Inner1 layers show higher crosstalk, indicating more signal interference.

✓Longer traces tend to have higher crosstalk, suggesting routing length impacts signal quality.

✓Filtering by layer helps focus on specific routing issues per PCB layer.

Bonus Challenge

Add a calculated measure to estimate signal delay based on trace length and visualize it.

Show Hint

Use formula: Signal Delay (ns) = Length (mm) / 150 (assuming signal speed 150 mm/ns). Create a new measure and add a bar chart by layer.