PCB LAYOUT & DESIGN
Coplanar Waveguide Printed Circuit Boards (CPW PCBs) are essential for high-frequency RF/microwave designs. Their unique grounded coplanar structure ensures superior signal integrity with minimal loss and low dispersion. This makes CPW PCBs ideal for high-speed communications.
The printed circuit board with application in the RF (radio frequency) or high frequency such as radar system, Wi-Fi, Bluetooth, wireless system, high frequency analog system, etc., all of these type of applications need to include measures to ensure signal integrity. It would be very difficult to many high frequency systems with micortrip or embedded microstrip routing on the surface copper layer. However, coplanar waveguide routing is an ideal solution and widely used to solve the signal integrity headaches.
Most PCB design software (such as Altium) can be used to define the coplanar waveguide layout with a ground pour feature printed circuit board. This will be easily for PCB designer to define a coplanar waveguide on the printed circuit board. But a frequently asked question: when should the circuit board designer use coplanar waveguide layout (routing)? Here’s everything you need to know that before starting a design PCB with coplanar waveguide track in.
A coplanar waveguide is a simple routing style where a signal trace is routed on the surface layer and surrounded by ground pour on each side. The role of the ground pour on each side of a signal trace is to provide natural shielding for the signal against interference from other traces on a circuit board. Additionally, a ground panel layer is needed to be routed below this signal trace to provide high isolation in the PCB layout, this is shown in the image below.
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Below is the exact printed circuit board layout in Altium tool:
Requires solving elliptical integrals for precise impedance control
Signal impedance is highly sensitive to trace-to-ground spacing (more than trace geometry)
Solution: Use specialized calculators (e.g., Altium’s built-in tool or open-source options like SourceForge) for CPW impedance modeling
ENIG plating increases insertion loss vs. microstrip
HASL offers lower loss but introduces surface roughness, degrading high-frequency performance
Recommendation: Below 100GHz, coating choice has minimal impact—optimize trace length instead
Implement coplanar waveguide design when:
1. 40% lower signal loss vs. microstrip at 10-100GHz
2. Superior impedance stability (±2% tolerance)
3. Component cost reduction (simplified grounding)
4. Cross-talk reduction in mixed-signal layouts
| Sector | Frequency Range | Use Case |
|---|---|---|
| 5G Infrastructure | 24-47GHz | mMIMO antenna arrays |
| Automotive Radar | 77-81GHz | ADAS collision avoidance |
| Satellite Comms | 30-50GHz | Low-noise downconverters |
As a China-based PCB manufacturer with global engineering support, Weller Technology optimizes CPW designs for aerospace, automotive, and 5G applications. Request a DFM review for your next high-frequency project.
