Webinar: How to Design PCB Transmission Lines with Controlled Impedance
REGISTER NOW
February 12th, 2025 | 10 AM PT
COST: FREE
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12
Days
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12
Hours
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46
Minutes
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8
Seconds
Brian Walker
Senior RF Engineer SME at Copper Mountain Technologies
Amit Bahl
CRO at Sierra Circuits
This webinar will be hosted on Zoom.
Following this event, you will receive:
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Recording
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Slides
Webinar abstract:
When designing circuits in the GHz range, ensuring uniform transmission line impedance becomes critical to maintain signal integrity. These traces play a key role in managing propagation delay, which is essential for synchronized data transfer.
In this webinar, you’ll learn the best practices for designing PCB transmission lines with controlled impedance.
How to design PCB transmission lines with uniform impedance
To design efficient high-speed traces, first, you need to evaluate the critical length (lc). It is the threshold value beyond which a trace behaves as a transmission line. Typically, lc is 1/6th of the signal’s operating wavelength. When signal lines exceed this length, you need to implement appropriate design rules to avoid impedance mismatches.
For achieving uniform impedance throughout the transmission line, select laminates with a low dielectric constant (Dk<4). Ensure the material’s Dk is consistent over the operating frequency and temperature ranges. To reduce signal attenuation, choose materials with a lower dissipation factor (Df<0.005).
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A well-planned stack-up is important for minimizing dielectric loss. Place high-speed layers adjacent to solid ground planes to lower parasitic inductance. Incorporate symmetrical stack-ups to avoid noise coupling.
Implement serpentine traces and meandering techniques to minimize propagation delay. Keep the spacing between serpentine loops at least three times the trace width to avoid coupling.
To ensure consistent impedance and reduce signal reflections, terminate the high-speed tracks correctly. A series termination involves placing a resistor close to the driver. Whereas, in shunt termination, a resistor is connected in parallel with the receiver. The choice of termination depends on the application and the characteristics of the signal.
To reduce conductor loss in PCB transmission lines, opt for ENEPIG and ENIG surface finishes as they minimize conductor resistance and help maintain uniform impedance.
Use time-domain reflectometry (TDR) and vector network analyzer (VNA) to detect any impedance discontinuities in your PCB transmission lines.
Register for this webinar to gain practical insights on designing transmission lines with controlled impedance from our PCB experts.
Webinar agenda:
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3 factors for analyzing PCB transmission line impedance
- ○ Signal speed and propagation delay
- ○ Critical length
- ○ Rise/fall time
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Losses in high-speed signal lines
- ○ Conductor/copper loss
- ○ Dielectric loss
- ○ Radiation loss
- ○ Total insertion loss
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Techniques to design PCB transmission lines with controlled impedance
- ○ Tips to select low-loss materials
- ○ Stack-up strategies to reduce dielectric loss
- ○ Serpentine routing and meandering
- ○ Transmission line termination methods
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Surface finish recommendations for high-frequency PCBs
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TDR and VNA for impedance analysis
Senior RF Engineer SME, Copper Mountain Technologies
Brian Walker is the Senior RF Engineer SME at Copper Mountain Technologies where he helps customers to resolve technical issues and works to develop new solutions for applications of VNAs in test and measurement. Previously, he was the Manager of RF design at Bird Electronics, where he managed a team of RF Designers and designed new and innovative products. Prior to that he worked for Motorola Component Products Group and was responsible for the design of ceramic comb-line filters for communications devices. Brian graduated from the University of New Mexico, has over 40 years of RF Design experience, and has authored 3 U.S. Patents.
Amit Bahl, CRO at Sierra Circuits
Amit Bahl, widely recognized as the PCB Guy, currently serves as the Chief Revenue Officer at Sierra Circuits. He earned his Bachelor of Science in Engineering from UCLA in 1997, launching his career in Silicon Valley's tech industry. In 2009, he assumed the role of Director of Sales and Marketing at Sierra Circuits, with a dedicated focus on democratizing design for manufacturing best practices and guidelines for PCB designers and engineers. Assuming the position of Chief Revenue Officer since 2022, Amit's mission persists: to simplify the PCB design journey for all stakeholders. His unwavering dedication continues to drive Sierra Circuits as a trusted resource for the PCB design community.
