GaN (Gallium Nitride) material is a fairly new substrate that is a perfect match for electronic applications that require improved performance especially in terms of high frequency, like the case of 5G applications. The realization of an electronic circuit that includes GAN components is very attractive because of the exceptional performance of this type of material: utilizing GaN as a substrate for the design of high frequency power amplifiers leads to a higher efficiency in power management with a wider broadband.This approach is a very good solution in terms of efficiency and linearity, as it is shown in a very interesting recent article:
“A design approach for a broadband, linear, efficient output back-off mode RF power amplifier (RFPA) emphasizes the importance of minimizing design uncertainties. Using this approach, excellent agreement between modeled and measured performance is achieved with a first-pass design. Demand for linear RFPAs covering the frequency range from 1.5 to 2.8 GHz is driving new design methods for broadband, linear and highly efficient RFPAs operating in output back-off mode. Improving efficiency in PAs has long been a challenge for designers, in part due to poor control of harmonic load impedances. The difficulty measuring waveforms at microwave frequencies makes it hard to determine if optimum wave shaping has been achieved. Broadband design adds a challenge when a harmonic of a lower operating frequency lies in the operating band. These inherent difficulties can be compounded by imprecise design techniques, leading to multiple time-consuming and expensive iterations. The effectiveness of this approach is demonstrated using a commercially available discrete 10 W GaN on SiC, packaged, high electron mobility transistor fabricated with a 0.25 µm process (Qorvo’s T2G6000528) and a 20 mil RO4350B printed circuit board. The fabricated RFPA achieves a peak power greater than 40 dBm and a peak drain efficiency greater than 54 percent over its operating bandwidth. In back-off mode, the RFPA achieves an uncorrected linearity of 30 dBc and drain efficiency of 34 percent or higher when driven with a 2.5 MHz, 9.5 dB peak-to-average power ratio (PAPR) COFDM signal in the 2.0 to 2.5 GHz band.” (Source: Microwave Journal)
The” Distributed load network loss and match (a) and transducer and operational power gain vs. frequency (b) “of a RF Power Amplifier built with GaN material. (Source: Designing A Broadband, Highly Efficient, GaN RF Power Amplifier By: J. Brunning and R. Rayit, SARAS Technology, Leeds, U.K.)
The utilization of a GaN substrate in electronic applications is not only useful for RF applications but recently this material has been selected to be qualified for automotive applications by means of the AEC specification:
… Several suppliers have now announced AEC qualification of GaN devices. “We have detailed test programs with all the automotive manufacturers for AEC Q+, they have all the test results,” said Witham. However, GaN is an enabling technology and that needs a broad portfolio, from wireless chargers in consumer designs to highly efficient converters in data centers. “The approach that we take is these are the basic building blocks for any power system from 25W to 25kW,” he said.” (Source: GaN Systems)
The Automotive environment is very demanding in terms of performance and robustness for ICs. The performance of GaN material and its comparison with Silicon and SiC materials in terms of on-state resistance vs. breakdown Voltage is shown in the following Figure 2:
“Silicon-based power transistors are reaching limits of operating frequency, breakdown voltage and power density in the power electronics industry and GaN’s performance is beginning to shine. By no means is silicon going extinct, but energy requirements are continuing to increase, thereby requiring new methods and materials to be investigated/used to meet these demands (Source: Transphorm) .”
What do you think about GaN’s potential as a substrate for new, challenging applications of electronics technology? Do you have any experience with GaN in system architecture?