How to Design PCB for HDMI: Key Steps and Best Practices

To design a PCB for HDMI, maintain a controlled impedance of 100 ohms differential for the TMDS pairs and carefully route high-speed differential pairs with matched lengths. Use proper ground planes, keep signal traces short, and follow HDMI specifications for connector placement and power filtering.

Syntax

Designing an HDMI PCB involves these key elements:

• Controlled impedance traces: Differential pairs with 100 Ω impedance.
• Trace length matching: Ensure differential pairs have equal lengths to avoid signal skew.
• Ground planes: Solid ground layers to reduce noise and interference.
• Connector footprint: Follow HDMI connector mechanical specs.
• Power filtering: Use decoupling capacitors near HDMI power pins.

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HDMI PCB Design Syntax:
- Define differential pairs with 100 Ω impedance
- Match trace lengths within ±5 mils
- Use continuous ground plane under HDMI signals
- Place HDMI connector footprint per datasheet
- Add 0.1 µF decoupling capacitors near power pins

Example

This example shows how to set up differential pairs and ground planes in a PCB design tool for HDMI signals.

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1. Create two traces for TMDS differential pair signals (e.g., TMDS+ and TMDS-).
2. Set trace width and spacing to achieve 100 Ω differential impedance (consult your PCB stackup).
3. Use the PCB tool's length tuning feature to match trace lengths within 5 mils.
4. Add a solid ground plane layer beneath the HDMI signal layer.
5. Place the HDMI connector footprint according to the manufacturer's datasheet.
6. Add 0.1 µF capacitors close to HDMI power pins for filtering.

Output

Result: Differential pairs with controlled impedance and matched lengths, solid ground plane, and correct connector placement ensure HDMI signal integrity.

Common Pitfalls

Common mistakes when designing HDMI PCBs include:

• Ignoring impedance control, causing signal reflections and errors.
• Unequal trace lengths in differential pairs leading to timing skew.
• Poor grounding causing electromagnetic interference (EMI).
• Placing HDMI connectors too close to board edges or noisy components.
• Skipping power supply decoupling near HDMI power pins.

Always verify your PCB stackup and use simulation tools if possible.

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Wrong way:
- Trace widths not set for impedance
- Differential pairs with large length mismatch
- No ground plane under HDMI signals

Right way:
- Calculate and set trace width/spacing for 100 Ω
- Match differential pair lengths within 5 mils
- Use continuous ground plane layer

Quick Reference

Design Aspect	Recommendation
Differential Pair Impedance	100 Ω differential
Trace Length Matching	Within ±5 mils
Ground Plane	Solid continuous layer under signals
Connector Placement	Follow HDMI datasheet footprint
Power Filtering	0.1 µF decoupling capacitors near power pins
Trace Routing	Keep short and avoid sharp bends

Key Takeaways

Maintain 100 Ω differential impedance for HDMI TMDS pairs.

Match differential pair trace lengths closely to prevent signal skew.

Use solid ground planes to reduce noise and EMI.

Place HDMI connectors and power filtering components per specifications.

Avoid common mistakes like impedance mismatch and poor grounding.