The Reality of GaN Integration: Why Faster Switching Demands Smarter System Design
For engineers, the conversation around GaN has definitely shifted from intrigue to integration. It is no longer about what the material can do, but about whether that capability can translate into a worthwhile improvement across the entire power system.
Faster switching can reduce switching losses and, in suitable designs, support higher switching frequencies. That may allow engineers to reduce the size of selected passive components, improve efficiency, or increase power density. However, none of these outcomes is guaranteed by the device alone.
There are design considerations that must be understood and addressed correctly throughout the design process. GaN, therefore, needs to be evaluated as part of the complete power architecture, rather than treated as an isolated replacement component.
Beyond a Simple Device Substitution
GaN is attractive because it gives engineers new ways to balance efficiency, switching frequency, size and thermal performance. Its switching characteristics can reduce losses during rapid transitions, while some implementations can avoid the body-diode reverse-recovery losses associated with silicon MOSFETs. Nevertheless, the value of those characteristics still depends on the selected device, voltage, operating conditions, and topology within the context of the application.
With silicon, engineers work from established gate-drive levels, package formats, protection methods, and layout practices. GaN does not offer one equivalent set of rules. The difference can be seen within Nexperia’s portfolio. Its enhancement-mode (e-mode) devices are normally off and designed for a 0-5 V gate drive, lower than that of typical silicon power semiconductors. Alternatively, Nexperia offers normally-on depletion-mode (d-mode) GaN paired with a low-voltage silicon MOSFET to create a normally-off switch that can use the more familiar 0-10 or 12 V drive[1]. This can ease migration from silicon, but it introduces a second die and different switching and reverse-conduction behaviour. Selecting “GaN” is, therefore, only the beginning. Engineers must decide which implementation suits the application.
That does not mean every GaN project demands a completely new architecture. Some designs can be adapted successfully, while others require more substantial changes. The integration effort tends to increase with the design's ambition. The more aggressively GaN’s switching performance is used, the more important it becomes to treat the device, driver, PCB, and control strategy as a single system.
Faster Switching Changes the Design Priorities
The importance of packaging is often underestimated. It determines the length of critical connections, the inductance within the switching loop, and how heat leaves the component. Familiar leaded packages can simplify assembly, reworking and heatsink mounting, but their longer connections can limit how effectively very fast switching is used. Compact surface-mount packages support tighter loops and can replace internal bond wires with copper clips, reducing parasitic inductance, but they place different demands on PCB layout, assembly, and cooling.
(Click to enlarge) Figure 1: Efficiency and power loss for GaN and a leading Silicon device tested in the same 100 kHz half-bridge boost converter. GaN achieves higher efficiency and lower losses across the measured output range. (Source: Nexperia)
The thermal route creates another choice. Bottom-side cooling can use the PCB copper and thermal vias, but this concentrates electrical and thermal demands in the same area of the board. Top-side cooling moves heat towards a heatsink or cold plate, with onsemi reporting that top-side cooling technology can provide up to 70% improvement in thermal performance[2], but it also introduces mechanical requirements around the thermal interface material, mounting pressure and tolerances. Package, PCB, and thermal design must therefore be considered together.
The level of device integration provides another option. Navitas offers power ICs that combine GaN switches with drive, level-shifting, sensing, and protection[3]. This removes some sensitive high-speed connections from the PCB and can shorten development, although it gives the designer less freedom to optimise each element independently.
The choice, therefore, depends on where the design team wants to carry the complexity. Greater integration can reduce external circuitry and layout sensitivity, while a discrete implementation provides more freedom to select and tune the driver, protection, and switching behaviour.
(Click to enlarge) Figure 2: Traditional cooling uses PCB vias. Top cooling allows direct to heatsink connection (Source: onsemi)
Whichever route is selected, validation cannot be left until the end. Reference designs provide a sound starting point, but fast switching must be measured on the real hardware. Probe loading, bandwidth, and the test fixture can change what the engineer sees. Several prototype iterations may be needed to balance efficiency, temperature, emissions, and robustness beyond a supplier’s proven platform.
Topology Determines Where GaN Creates Value
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With the ongoing shift to renewable energy and the electrification of transport and industry, the demand for higher power and greater energy efficiency in electronics is increasing. Wide bandgap technologies including SiC and GaN bring many advantages.
WBG OVERVIEWIdeally, the application should therefore drive the technology decision to ensure that GaN’s switching performance creates enough value to justify a different package, driver, layout, or validation process. Even where GaN is selected, the best system may not be the one operating at the highest possible frequency.
Motion control illustrates this well. In a power supply, a higher frequency can reduce the size of selected magnetic components. In a motor drive, the motor is already the principal passive component and will not become smaller simply because the inverter switches faster. The motor windings, cabling and electromagnetic compatibility (EMC) requirements may instead set a practical limit on voltage slew rate and switching frequency.
STMicroelectronics has demonstrated the potential system-level value in a 1 kW motor-control platform operating at 8 kHz. At a measured output of 695 W, it achieved 97.9% efficiency without a heatsink. The example shows that the value of GaN in motor control can come from reducing losses and cooling requirements, rather than simply increasing switching frequency[4].
In power supplies, bidirectional GaN can replace the two back-to-back unidirectional switches normally needed to control current in both directions. This can reduce component count, footprint, and losses, while supporting more compact single-stage AC/DC and DC/AC designs for applications such as solar microinverters, battery systems, infrastructure power supplies, and onboard chargers. However, the surrounding topology, control, and protection must still manage power flow and faults in both directions, which can increase the complexity of design and validation.
These examples underscore why GaN integration is not a single standard engineering process. Device structure, package, topology, and application determine where the technology creates value and which surrounding changes are justified.
Turning Device Performance into System Performance
The expanding choice of discrete devices, integrated power ICs, packages and supporting components is making supplier knowledge more important, not less. Avnet Silica can help engineers identify which approach best fits the application, then move from component selection into reference hardware, prototyping and supplier-level technical support. The objective is not to switch as quickly as possible, but to determine where GaN can deliver a measurable and defensible improvement across the complete system.
[1] https://assets.nexperia.com/documents/leaflet/nexperia_document_leaflet_GaNFETs_2024.pdf
[3] https://my.avnet.com/silica/products/new-products/npi/2022/navitas-half-bridge-power-ics/
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