Microchip Boosts GaN-on-SiC with MMIC for Satellite and 5G

Article By : Maurizio Di Paolo Emilio

Microchip's MMIC power amplifier leverages GaN-on-SiC technology to meet the stringent performance requirements of satellite communications.

Modern satellite systems are based on geostationary constellations that offer excellent coverage of the earth’s surface and fast broadband data transmission. Leveraging Ka-band and high RF output power, Microchip Technology’s new GMICP2731-10 MMIC power amplifier helps meet the stringent performance requirements of satellite communications by leveraging GaN-on-SiC technology.

In an interview with EE Times, Mike Ziehl, senior manager of product marketing at Microchip Technology, highlighted the features of this new model and the upcoming applications in the aerospace field and 5G. The new device is the first gallium nitride (GaN) monolithic microwave integrated circuit (MMIC) from Microchip for the satellite communications market. The technology used is 0.15 μm GaN-on-SiC and provides an output power of up to 10 W in the 27.5 to 31 GHz band.

The satellite communications industry has progressively moved to higher frequency bands to support the growing demand for bandwidth, including the X, Ku, K and Ka bands. GaN supports high throughput higher power and wide bandwidth in these frequencies.

GaN-on-SiC for RF
RF architectures need to be scalable, efficient, and extremely compact. 5G will require densification not only at the macro level with the installation of more base stations but also high power density at the device level. To meet the needs of lower power consumption, smaller form factors, and better performance in terms of thermal management, RF power amplifiers based on GaN are expected to become mainstream in the market for its improved power performance.

“Our initial focus was on Ka-band satellites. But, customers found the product suitable for 5G as well, depending on the country of operation,” said Ziehl.

Gallium nitride solutions have emerged as an important component for 5G RF and satellite communications. The question is which substrate to apply. GaN-on-SiC has three times the thermal conductivity of GaN-on-Si, thus allowing devices to operate at a much higher voltage and higher power density with less heat dissipated.  In addition, the chemical structure of GaN-on-SiC allows devices to be created without defects in the crystals, in contrast to silicon which does not align well with GaN.

Improved energy density allows smaller solutions to be built, thus saving not only cost but also weight, which is especially important in aerospace applications.  GaN-on-SiC is robust with minimal performance degradation. Technology research shows that while GaN offers slightly better efficiency than GaAs for similar power output, the size reduction due to higher power density and thermal performance can be as much as 70%.

Microchip Solution
The GMICP2731-10 works across the 3.5 GHz bandwidth, and Its power-added efficiency is 20%, and it achieves 39 dBm saturated output power from 27.5-31GHz and 15 dB of return loss. A balanced architecture allows the GMICP2731-10 to be well matched to 50 ohms and includes integrated DC blocking capacitors at the output to simplify design integration.

“It is possible to monitor the instantaneous output power with a corresponding pin so that appropriate decisions can be made by a sensor or microprocessor acting on this pin,” said Ziehl.

Figure 1: 27GHz- VD=24V IDQ=100mA Temperature=25ºC (Source: Microchip)


Figure 2: 31GHz- VD=24V IDQ=100mA Temperature=25ºC (Source: Microchip)

Complex modulation schemes such as 128-QAM and increasingly efficient demands for solid-state technology have led designers down new paths to meet market demands. The geometry used is chosen according to the operating frequency, in this case, a layer of 0.15 μm is adopted to meet satellite requirements.

Microchip highlighted that high-power GaN MMICs can achieve more than 30 percent lower power and weight than their GaAs counterparts, a gain for satellite OEMs. Microchip is offering a demo board for those unfamiliar with the technology and, therefore, to speed up the time-to-market of the product. “Figure 3 shows the board with its RFA connectors with a die sitting in the middle, relatively easy to connect and use. Bring up the drain voltage at 24 volts and then adjust the gate more positive until you see about 110 milliamps of current. And then make sure you’re under the current limit, which we say is five amps,” said Ziehl.

Figure 3: GMICP2731-10 Evaluation Board (Source: Microchip)

Material suppliers are implementing new manufacturing solutions to offer lower costs and easier adoption. In particular, further progress is expected in the manufacturing process of GaN compound semiconductors. As silicon hits its application limits both in power and in frequency, GaN and SiC technologies are positioned for dominance in power electronics applications, where their characteristics suit requirements for compactness, lightweight, high efficiency, and high-density power. Technological challenges persist, notably in the areas of cost reduction and total heat dissipation, which in the case of semiconductors stems from conduction and switching losses.

This article was originally published on EE Times.

Maurizio Di Paolo Emilio holds a Ph.D. in Physics and is a telecommunication engineer and journalist. He has worked on various international projects in the field of gravitational wave research. He collaborates with research institutions to design data acquisition and control systems for space applications. He is the author of several books published by Springer, as well as numerous scientific and technical publications on electronics design.

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