As broadband networks evolve toward multi-gigabit speeds and power-hungry features like PoE++, mesh Wi-Fi, and edge AI, Customer Premises Equipment (CPE) must deliver more performance in smaller, more efficient packages. This puts unprecedented demands on the power supply unit (PSU)—where Gallium Nitride (GaN) is emerging as a transformative alternative to traditional silicon.
But is GaN the right fit across all CPE tiers? This article explores the technical benefits, challenges, a head-to-head comparison with CoolMOS, and strategic options for OEMs navigating this fast-moving landscape.
What Is GaN?
Gallium Nitride (GaN) is a wide bandgap semiconductor known for its high electron mobility and breakdown voltage. These characteristics allow power transistors to switch faster and more efficiently than conventional silicon (Si) MOSFETs, enabling compact, high-frequency, high-efficiency power designs.
Pros of GaN for CPE Power Supplies
- Exceptional Efficiency
GaN-based converters routinely achieve 94–96% peak efficiency, reducing thermal stress and energy loss. - Compact Design
High-frequency operation enables smaller transformers and passive components—translating to smaller, lighter PSUs, ideal for wall-plug and desktop CPE adapters. - Thermal Performance
Lower conduction and switching losses lead to cooler operation, extending product lifespan and reliability. - Performance Scalability
Ideal for advanced CPE (e.g., Wi-Fi 6E, xPON ONTs, edge AI gateways) that demand higher wattage and tighter thermal envelopes.
Challenges of GaN for CPE
- Higher Initial Cost
GaN switches typically remain 2–5× more expensive than silicon-based counterparts, depending on voltage class and packaging. - EMI Management
High-speed switching increases electromagnetic interference, necessitating careful layout, shielding, and filtering. - Ecosystem Maturity
GaN controller ICs, drivers, and protection mechanisms are still maturing, especially compared to the decades of optimization around Si. - Suboptimal for Low Wattage
For <15W CPE devices, GaN often doesn’t justify the added cost or complexity, with limited efficiency gain.
GaN vs. CoolMOS for CPE Applications
While GaN continues to gain traction, CoolMOS (Infineon’s high-voltage superjunction MOSFET technology) remains the dominant incumbent in CPE applications. Here’s a direct comparison:
Frequency & Size Advantage
- GaN supports switching frequencies >1 MHz, enabling use of smaller magnetics and overall power stage footprint.
- CoolMOS is typically limited to hundreds of kHz, requiring larger passives.
Cost & Long-Term Potential
- Today: GaN and CoolMOS can be cost-comparable in certain high-volume or integrated packages.
- Future: As integration increases, GaN has stronger potential to reduce system-level cost via smaller BOM and better thermal management.
Surge Testing & Safety
- GaN has passed initial 6kV surge withstand testing in limited samples.
- However, CoolMOS has full production-level surge and field reliability data, making it the safer choice for mass-market designs today.
Reliability & Deployment Readiness
- CoolMOS benefits from a mature supply chain, proven silicon physics, and a large pool of application reference designs.
- GaN still requires deeper design validation and long-term field data to achieve widespread CPE adoption.
Alternative Technologies
| Technology | Use Cases | Pros | Cons |
| Silicon MOSFETs | Basic DSL routers, low-power CPE | Ultra-low cost, mature ecosystem | Low switching speeds, less efficient |
| Silicon Carbide (SiC) | High-voltage outdoor/industrial CPE | Excellent thermal and voltage resilience | Overkill and too expensive for indoor CPE |
| Integrated Power ICs | Compact wall warts, mid-power routers | Small footprint, lower BOM, good thermal control | May limit design flexibility or max output power |
OEM Strategic Considerations
The optimal power technology should align with the CPE device’s market tier, thermal constraints, and cost envelope. Below is a practical breakdown:
| Application | Power Range | Recommended Tech | Rationale |
| Fiber ONT / xPON | 15–65W | ✅ GaN | High efficiency, small footprint, better thermal headroom |
| Wi-Fi 6E Router | 20–40W | ✅ GaN / Integrated | 24/7 power demand benefits from thermal and size advantages |
| DSL Modem | <15W | ❎ Si MOSFET / CoolMOS | Cost-sensitive, no need for GaN’s performance overhead |
| Entry-Level IoT Hub | <12W | ❎ Si / Integrated IC | Tight BOM constraints, minimal performance requirements |
| Industrial/Edge Gateway | >65W | ✅ GaN or SiC | Requires thermal robustness and long-life reliability |
Conclusion
GaN is no longer theoretical in CPE—it’s proving itself in high-performance applications where efficiency, size, and thermal headroom are mission-critical. However, CoolMOS remains the workhorse for mainstream applications thanks to its proven reliability, EMI stability, and cost structure.
Key Takeaways:
- Use GaN when: You need compactness, high power density, and excellent efficiency in thermally constrained designs.
- Use CoolMOS when: Cost, reliability, and proven validation are the top priorities—especially in legacy or mass-market CPE.
- Evaluate strategically: Match the power technology to the product tier, not just the spec sheet.
As GaN costs fall and validation expands, its adoption will grow—especially for premium CPE. For now, CoolMOS and Si remain essential tools in the OEM toolkit, with GaN ready to disrupt where the application justifies it.
