May 2020

www.infineon.com/gan POWER GAN 25 www.power-mag.com Issue 2 2020 Power Electronics Europe (Figure 2). Not only will additional hardware be required to implement 5G, but the stations themselves will require more compute power to support the wider range of services that the new generation of mobile broadband will offer. As operators begin to deploy edge computing, the power architecture for each station will need careful consideration. More power density, less heat? It’s clear from the points covered that some tough design challenges lie ahead. Support for the necessary power input can only be achieved by increasing the efficiency of the power conversion stage and will be instrumental to delivering more power in the same footprint. The key to this efficiency lies in a combination of gallium nitride (GaN) wide bandgap semiconductor technology and cutting-edge surface-mount design (SMD) packaging. Unlike through-hole devices (THDs), SMDs are mounted directly on the surface of the PCB. The elimination of through-holes and leads as well as increased function density makes more space available on the board, thereby increasing power density capabilities. However, increased power density can be a double-edged sword as it is usually delivered hand-in-hand with corresponding heat density. Packing more power into a given area can only be advantageous when heat density can be kept the same or, if possible, be decreased. SMD packaging offers a significant benefit in this regard as it allows for top-side cooling by putting the top of the package in direct contact with the enclosure, which is usually made of aluminum. This offers a much shorter thermal path for the heat to escape from the transistor junction to ambient air. Using traditional Silicon semiconductors in SMDs will not be able to deliver lower heat density. Even though packaging technology continuously improves to offer better thermal conductivity, the device will still be limited by the operating temperature unless the semiconductor material inside switches more efficiently. Although Si MOSFETs have reached their upper limits of efficiency, new wide bandgap semiconductors such as silicon carbide (SiC) and GaN offer much higher efficiency. In SMD packaging, GaN has certain physical properties that allow it to switch higher powers at higher frequencies than its Si counterparts, as well as offering a lower on-resistance (R DS(on) ) and significantly lower switching losses. Because the power converter can operate at higher frequencies, the power supply topology is simplified due to the lower number of magnetic discrete components required in the circuit, thereby allowing for greater power density. Moreover, GaN’s inherent high efficiency means heat density can, in most cases, be reduced. Figure 3 shows a Pareto analysis of all possible power density and efficiency combinations of a 3 kW 48 V PSU at 50 % load. It demonstrates that using Infineon’s CoolGaN in power conversion solution could either result in higher efficiency, higher power density or a combination of both when compared to even the most state-of-the-art Si MOSFET solutions. It is clear therefore to see that GaN in SMD packages are a perfect match for the particular requirements of 5G network infrastructure and enable network operators to deliver the power of 5G even in the most challenging places References [1] Wall Street Journal, November 11, 2019 (https://www.wsj.com/articles/u-s- government-is-tripping-over-itself-in-race- to-dominate-5g-technology- 11573527840) [2] New York Times, July 16, 2019 (https://www.nytimes.com/2019/07/16/s cience/5g-cellphones-wireless- cancer.html) [3] The Verge, August 13, 2018 (https://www.theverge.com/2018/8/13/1 7686310/huawei-zte-us-government- contractor-ban-trump) Figure 3: GaN can provide higher power density and greater conversion efficiency Figure 2: SMPS in the 5G ecosystem