Contents 

  Key factors to consider while designing high-speed signal paths 

■ Critical length: Trace length should be less than lc 

■ 3 dB bandwidth: To avoid signal attenuation  5 high-speed trace design techniques to ensure signal integrity 

■ 1. Implement serpentine routing for length-matching 

■ 8 best tips to design serpentine traces  

■ 2. Include guard traces to manage crosstalk 

■ 6 guidelines to implement guard traces  

■ 3. Terminate traces to prevent signal reflections 

■ Series trace termination 

■ Parallel/shunt trace termination  

■ 4. Optimize the trace geometry to ensure consistent impedance 

■ 5. Never split ground planes 

■ 6 best grounding practices to ensure signal integrity and minimize EMI   5 high-current trace design techniques to ensure power integrity 

■ 1. Calculate trace current-carrying capacity 

■ 2. Use wider traces 

■ 3. Place the thermal vias near the hotspots 

■ 4. Place decoupling capacitors near the power supply 

■ 5. Optimize via current-carrying capacity  5 best DFM guidelines for high-speed and high-current PCB traces 

■ 1. Stick to the manufacturer’s minimum/maximum line width capabilities 

■ 2. Maintain sufficient trace spacing based on the start copper thickness 

■ 3. Provide at least 7 mil trace-to-board edge spacing for outer layers and 10 mil for inner layers 

■ 4. Ensure at least 15 mil clearance between the copper feature and the v-score line 

■ 5. Have a minimum of 8 mil drill-to-copper clearance to avoid short circuits

  When designing PCBs for frequencies over 5 GHz and current above 2A, trace design becomes paramount. 

To ensure signal integrity and reliable power delivery, optimize the trace width, spacing, and impedance of high-frequency and high-current traces. 

  Highlights: 

When designing high-speed and high-current PCB traces: 

• Implement serpentine routing, guard traces, and maintain uniform impedance to ensure signal integrity. 

• Optimize trace geometry and ground planes for efficient signal propagation. 

• Place decoupling capacitors near power supplies to prevent voltage drops. 

• Employ thermal vias and copper pours for effective heat dissipation.  

In this article, we will first cover 5 best practices for high-speed traces and move on to 5 essential guidelines for high-current traces. At the end, you will find 5 DFM guidelines. 

  Watch the full webinar here: How to design high-speed and high-current PCB traces.

   Key factors to consider while designing high-speed signal paths

Signal integrity becomes significant as signal speeds increase. Let’s dive into the factors you must check before designing high-speed signals for signal integrity. 

Critical length: Trace length should be less than lc The critical length (lc) is the trace length above which a trace must be designed as a PCB transmission line with controlled impedance. 

  If a trace is longer than the critical length, it might cause signal reflections if the impedance is inconsistent. Conversely, if the trace length is less than the critical length, the signal can be transmitted without distortion. 

For analog signals, the critical length is given by: 

lc =