Long-range wireless link with fiber-equivalent data rate

In this paper, we present a high-efficiency S-band gallium nitride (GaN) power amplifier (PA). This amplifier is fabricated based on a self-developed GaN high-electron-mobility transistor (HEMT) with 10 mm gate width on SiC substrate. Harmonic manipulation circuits are presented in the amplifier. The matching networks consist of microstrip lines and discrete components. Open-circuited stub lines in both input and output are used to tune the 2nd harmonic wave and match the GaN HEMT to the highest efficiency condition. The developed amplifier delivers an output power of 48.5 dBm (∼70 W) with a power-added efficiency (PAE) of 72.2% at 2 GHz in pulse condition. When operating at 1.8–2.2 GHz (20% relative bandwidth), the amplifier provides an output power higher than 48 dBm (∼ 65 W), with a PAE over 70% and a power gain above 15 dB. When operating in continuous-wave (CW) operating conditions, the amplifier gives an output power over 46 dBm (40 W) with PAE beyond 60% over the whole operation frequency range.

This work presents radio-frequency-microelectromechanical-system (RF-MEMS)-based tunable matching networks for a multi-band gallium nitride (GaN) power amplifer (PA) application. In the frequency range from 3.5–8.5 GHz return losses of 5–10 dB were measured for the input network, matching impedances close to the border of the Smith chart. For the output matching network return losses of 10–20 dB and insertion losses of 1.3–2 dB were measured. The matching networks can tune the PA to four different operating frequencies, as well as changing the transistor's mode of operation from maximum delivered-output-power to maximum power-added-efficiency (PAE), while keeping the operating frequency constant. Furthermore, different single pole double throw (SPDT)-switches are designed and characterized, to be used in frequency-agile transmit/receive-modules (T/R modules).

The power, efficiency, and bandwidth performance improvements demonstrated by gallium nitride (GaN) material and technology are currently being utilized by state-of-the-art microwave power amplifiers in the latest generation of radar systems. High-power wide bandgap semiconductors play an important role in radar performance. For example, in a phased array radar, the RF energy is distributed to each element, phase shifted, and then amplified before being radiated. Throughout the 1990s, gallium arsenide (GaAs) had been the semiconductor of choice for efficiently amplifying this signal; however, as the performance requirements of these systems continued to increase to meet ever-growing threats, the industry began turning to GaN as an alternative semiconductor of choice.GaN has a significantly wider bandgap compared to GaAs, and GaN has a higher saturation velocity, a higher breakdown electric field, and better thermal conductivity in comparison to GaAs. As a result, GaN produces a 5× increase in output power over GaAs that enables radars to search 5× the volume in the same time, increase their effective range by 50%, or reduce their size by 50% depending on the specific application. AlGaN/GaN high electron mobility transistors (HEMTs) became the early heterostructure of choice providing RF output densities >6 W/mm at microwave and millimeter wave frequencies and high conductivity SiC substrates with a 7-8× improvement in thermal conductivity became the early substrate of choice. However, significant material and substrate issues needed to be solved before the reliability and yield of GaN transistors were sufficient to meet the stringent needs required in defense systems.Today, GaN power amplifier technology continues to evolve as solutions to push performance higher are sought through material choices resulting in larger current densities, through design changes enabling higher operating voltages, through process and transistor designs providing more efficient operation, and through various material advances to improve heat dissipation. In this presentation we will provide an overview of GaN technology development at Raytheon covering the early motivation, material challenges, and insertions as they relate to the issues faced today.

Wide band-gap (WBG) semiconductors technology represents a potential candidate to displace conventional silicon (Si) technology used in power electronics. Between Silicon Carbide (SiC) and Gallium Nitride (GaN) power semiconductors, the latter is the least mature of both technologies, with many open research problems, especially in the aerospace industry. In this paper, we address the design and implementation of a DC/DC converter for a hybrid small unmanned aerial vehicle (UAV) based on GaN technology. Both theoretical and simulation comparisons of Si, SiC and GaN transistors for the converter are presented. The conclusion is that GaN devices are the most appropriate to fulfill converter requirements for the size and weight limitations of the selected UAV. The paper presents a buck converter which handles an input voltage range of 32 V to 40 V and provides a 12 V regulated output and output power up to 60 W. The experimental results carried out on the prototype converter show how promising the GaN technology is for aerospace systems, not only regarding its volume and size, but also its efficiency. Besides, practical implementation details are reported to contribute to the design of small, light and reliable GaN power converters for aeronautics.

: A key component of microwave telecommunication systems is the power amplifier (PA). The design parameters of a communication system, such as link performance, power budget, and thermal design are typically driven by the power amplifier's linearity, output power, and efficiency. These design parameters of PA are the key to ensuring an efficient system because the PA is the most power-consuming circuit in the communication system. In an effort to have students involved in this research area, the International Microwave Symposium (IMS) sponsored by IEEE Microwave Theory and Technique Society (MTT-S) has introduced a High Efficiency Power Amplifier Design Competition. In this report, we present a 2.8-GHz, 5-W, highly efficient PA based on a wide bandgap gallium nitride (GaN) high electron mobility transistor (HEMT) device (CGH 40010f from CREE). The PA design was presented at the 2010 IMS Student Design Competition and achieved the competition goal of output power greater than 5 W with a measured power added efficiency (PAE) of 61% at 2.8 GHz.

In order to meet the requirements of high efficiency and broadband for the wireless communication system, a high efficiency and broadband gallium nitride power amplifier (PA) is designed and verified. Using the step-matching structure, its bandwidth has been improved. Furthermore, its input matching network is constructed by connecting several microband lines serially to reduce the matching Q value. Meanwhile, the harmonic control network is designed as the output matching network, which is built by a quarter-wave (λ/4) line open circuit and short circuit microwave lines in parallel. Thus, its drain efficiency (DE)can be improved. This design is simulated and tested at 2.2–3 GHz with the gallium nitride (GaN) process. After measuring, it attains an output power (Pout) of 39.5–41.5 dBm, Gain of 10.5–12.5 dB, DE of 65.1%–78.3% with power added efficiency (PAE) of 64.8%–76.2%.

We fabricated a wideband gallium nitride (GaN) power amplifier (PA) using a power combiner with impedance transformation function. We designed a four-way planar impedance transformer power combiner based on the transmission line transformer (TLT) technique. The fabricated PA exhibited an average output power (Pout) of 233 W, average power-added-efficiency (PAE) of 42 %, and average drain efficiency (η) of 47% in the frequency range of 0.5 GHz to 2.1 GHz. The fabricated P A exhibits a wider fractional bandwidth (FBW) than a reported P A with an output power of over 200 W.

This paper presents a new class of power amplifier (PA) - Class-iF- <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> - resolving the highly nonlinear double inflection characteristics in the conventional Class-F- <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> PA. It is illustrated that, by properly terminating the second harmonic source impedance Z <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2S</inf> from conventional short-circuit to open-circuit, the double inflection nonlinear gain profile can be mitigated in the proposed Class-iF- <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> PA, wherein the same saturation output power is achieved with less gain compression without drain efficiency trade-off. The idea was validated with source/load-pull and a broadband prototype operating from 2.0 to 2.6 GHz was designed using a commercial 10-W Gallium Nitride (GaN) transistor. Under continuous wave (CW) signal test, the proposed Class-iF- <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> PA can achieve 40.1-40.8-dBm output power, 71.2%-77.3% drain efficiency (DE) and 67.4%-74.1 % power added efficiency (PAE) at 3-dB gain compression level over 2.0-2.6 GHz.

In this article, we present the analysis, design, and implementation of a wideband 10-W monolithic microwave integrated circuit power amplifier (PA), fabricated in a low-cost 0.1-μm gallium nitride (GaN) on Si technology. The design is focused on the realization of a low-loss and wideband impedance transformation networks across 2-20 GHz using a reactive matching (RM) technique. The two-stage GaN PA achieves an average output power of 40.1 dBm and a peak output power of 41.6 dBm at 13 GHz, in the CW-mode operation, with a smallsignal gain of S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> > 25.5 dB over the entire bandwidth. The average power-added efficiency (PAE) is 21%, with a peak PAE of 29% at 6 GHz. The PA chip occupies an area of 2.9×2.6 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . To the best of our knowledge, the PA presented in this work demonstrates the highest broadband gain among the reported GaN-based RMPAs with a corresponding output power of about 10 W.

For the high power millimeter wave applications, the useful wave source is the gyrotron. Normally the output wave of the gyrotron is the linear polarization wave. However, sometimes we need circular or elliptical polarization wave to match with the load. The polarization of the wave can be controlled with the polarizer to obtain the desired polarization parameters. The most common polarizer for the high power millimeter wave system is the rectangular grooved polarizer with round edges. This kind of the polarizer is easy to be fabricated and also has the high power capability.

This letter presents a novel technology for the integration of gallium nitride (GaN) power devices with silicon control circuits. It comprises stacked GaN power transistors and bipolar-CMOS-double-diffused metal-oxide-semiconductor (DMOS) (BCD) circuits. It leverages on both advantages of the high-voltage low-loss GaN devices and the high-integration BCD circuits. Using conventional manufacturing, packaging, and assembly techniques and equipment, the proposed technology is technology transferrable and applicable for commercial power electronic applications. To validate the concept, a 3.3–70 V dc–dc boost converter is designed, implemented, and verified experimentally. It features a conversion efficiency of 70.3%, output power of 1.68 W, and compact size of ${\text{0.32}}\times {\text{0.18}}\,{\text{cm}}^{2}$ .

A two-stage power amplifier (PA) using GaN HEMTs is presented with a high power added efficiency (PAE) and good linearity. This PA employs a structure of a class-C PA driving a class-AB PA to obtain a high PAE while maintaining the linearity. Source-pull and load-pull techniques were implemented to achieve optimum output impedance and inter-stage matching condition to compromise the PAE and the linearity of the overall circuit. When producing a two-tone carrier-to-intermodulation (C/I) ratio of 30 dB with the 1 MHz space, the two-stage PA exhibits a maximum PAE of 47% with an output power of 3 W at 3.7 GHz. The PA provides a maximum output power of 7 W with the gain of 15.8 dB.

Adversarial attacks and active defense on deep learning based identification of GaN power amplifiers under physical perturbation

The ultimate objective of this work was to develop a demonstrator of a highly efficient, GaN based, linearised, passively cooled solid-state power amplifier (SSPA)for avionic SATCOM terminals operating in L-band. The SSPA should provide sufficient output power to comply with all SATCOM classes in all installation options, meet all in-band and out-of-band distortion limits such as error vector magnitude (EVM)and spectral regrowth, and guarantee reliable operation for 1M-hours. The contract, undertaken with European Space Agency (ESA)funding, mandates the use of Gallium Nitride (GaN)technology and power amplifier linearisation techniques to maintain high efficiency, while operating in a linear fashion. The SSPA needs to meet all requirements without any forced-air cooling. The project has been completed successfully, achieving the 47% PAE target, while amplifying a single-carrier test waveform (Inmarsat R20T4.5X type waveform with 16-QAM modulation and 151.2kS/s symbol rate)to ~ 15W nominal / ~ 65W peak power level. Digital predistortion (DPD)linearisation was used to achieve <; 2% EVM and > 10dB margin in spectral regrowth measured against the ETSI (European Telecommunication Standards Institute)and Inmarsat channel masks at all offset frequencies. Passive cooling was demonstrated with GaN junction temperature not exceeding 150°C (absolute maximum rating 275°C)and mean-time-to-failure (MTTF)reliability of more than 10M hours.

This paper presents a high efficiency class-E power amplifier (PA) suitable for wireless transmitters operating at 2 GHz. Compact impedance transformation network is designed, using micro-strip transmission lines, so that it simultaneously achieves fundamental load transformation and harmonic impedance control using only two open-circuit stubs (2fo, 3fo). The dimensions of the network’s elements were determined in order to concurrently attain a high harmonic suppression, minimum loss and high power added efficiency. The measurement results of the PA prototype, which is designed using a 10 W Gallium Nitride (GaN) HEMT transistor, showed state-of-the-art drain and power added efficiency (PAE). The achieved PAE, power gain and output power, when the drain is biased at 50V, were equal to 74%, 12.6 dB and 11.4W respectively. In addition, a second and third harmonic suppression in excess of −40 dBc and −75 dBc, respectively, is achieved without extra circuit tuning or additional filtering.