Showing papers by "Mitsubishi Electric published in 2021"

Emerging GaN technologies for power, RF, digital, and quantum computing applications: Recent advances and prospects

Abstract: GaN technology is not only gaining traction in power and RF electronics but is also rapidly expanding into other application areas including digital and quantum computing electronics. This paper provides a glimpse of future GaN device technologies and advanced modeling approaches that can push the boundaries of these applications in terms of performance and reliability. While GaN power devices have recently been commercialized in the 15–900 V classes, new GaN devices are greatly desirable to explore both higher-voltage and ultra-low-voltage power applications. Moving into the RF domain, ultra-high frequency GaN devices are being used to implement digitized power amplifier circuits, and further advances using the hardware–software co-design approach can be expected. On the horizon is the GaN CMOS technology, a key missing piece to realize the full-GaN platform with integrated digital, power, and RF electronics technologies. Although currently a challenge, high-performance p-type GaN technology will be crucial to realize high-performance GaN CMOS circuits. Due to its excellent transport characteristics and ability to generate free carriers via polarization doping, GaN is expected to be an important technology for ultra-low temperature and quantum computing electronics. Finally, given the increasing cost of hardware prototyping of new devices and circuits, the use of high-fidelity device models and data-driven modeling approaches for technology-circuit co-design are projected to be the trends of the future. In this regard, physically inspired, mathematically robust, less computationally taxing, and predictive modeling approaches are indispensable. With all these and future efforts, we envision GaN to become the next Si for electronics.

Collisional history of Ryugu’s parent body from bright surface boulders

Abstract: The asteroid (162173) Ryugu and other rubble-pile asteroids are likely re-accumulated fragments of much larger parent bodies that were disrupted by impacts. However, the collisional and orbital pathways from the original parent bodies to subkilometre rubble-pile asteroids are not yet well understood1–3. Here we use Hayabusa2 observations to show that some of the bright boulders on the dark, carbonaceous (C-type) asteroid Ryugu4 are remnants of an impactor with a different composition as well as an anomalous portion of its parent body. The bright boulders on Ryugu can be classified into two spectral groups: most are featureless and similar to Ryugu’s average spectrum4,5, while others show distinct compositional signatures consistent with ordinary chondrites—a class of meteorites that originate from anhydrous silicate-rich asteroids6. The observed anhydrous silicate-like material is likely the result of collisional mixing between Ryugu’s parent body and one or multiple anhydrous silicate-rich asteroid(s) before and during Ryugu’s formation. In addition, the bright boulders with featureless spectra and less ultraviolet upturn are consistent with thermal metamorphism of carbonaceous meteorites7,8. They might sample different thermal-metamorphosed regions, which the returned sample will allow us to verify. Hence, the bright boulders on Ryugu provide new insights into the collisional evolution and accumulation of subkilometre rubble-pile asteroids. The Hayabusa2 team has discovered two types of bright boulder on the dark, carbonaceous asteroid Ryugu. One type has a spectrum consistent with material from an anhydrous silicate-rich asteroid, likely introduced by one or more collisions in Ryugu’s past.

Thermally altered subsurface material of asteroid (162173) Ryugu

Abstract: Analyses of meteorites and theoretical models indicate that some carbonaceous near-Earth asteroids may have been thermally altered due to radiative heating during close approaches to the Sun1–3. However, the lack of direct measurements on the subsurface doesn’t allow us to distinguish thermal alteration due to radiative heating from parent-body processes. In April 2019, the Hayabusa2 mission successfully completed an artificial impact experiment on the carbonaceous near-Earth asteroid (162173) Ryugu4,5, which provided an opportunity to investigate exposed subsurface material and test potential effects of radiative heating. Here we report observations of Ryugu’s subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. The strength and shape of the OH feature suggests that the subsurface material experienced heating above 300 °C, similar to the surface. In contrast, thermophysical modelling indicates that radiative heating cannot increase the temperature above 200 °C at the estimated excavation depth of 1 m, even at the smallest heliocentric distance possible for Ryugu. This supports the hypothesis that primary thermal alteration occurred on Ryugu’s parent body. Hayabusa2 created an artificial crater on Ryugu to analyse the subsurficial material of the asteroid. Results show that the subsurface is more hydrated than the surface. It experienced alteration processes that can be traced back to Ryugu’s parent body.

Anomalously porous boulders on (162173) Ryugu as primordial materials from its parent body

Abstract: Planetesimals—the initial stage of the planetary formation process—are considered to be initially very porous aggregates of dusts1,2, and subsequent thermal and compaction processes reduce their porosity3. The Hayabusa2 spacecraft found that boulders on the surface of asteroid (162173) Ryugu have an average porosity of 30–50% (refs. 4–6), higher than meteorites but lower than cometary nuclei7, which are considered to be remnants of the original planetesimals8. Here, using high-resolution thermal and optical imaging of Ryugu’s surface, we discovered, on the floor of fresh small craters ( 70%, which is as high as in cometary bodies. The artificial crater formed by Hayabusa2’s impact experiment9 is similar to these craters in size but does not have such high-porosity boulders. Thus, we argue that the observed high porosity is intrinsic and not created by subsequent impact comminution and/or cracking. We propose that these boulders are the least processed material on Ryugu and represent remnants of porous planetesimals that did not undergo a high degree of heating and compaction3. Our multi-instrumental analysis suggests that fragments of the highly porous boulders are mixed within the surface regolith globally, implying that they might be captured within collected samples by touch-down operations10,11. The Hayabusa2 spacecraft found dark boulders with very high porosity (>70%, as high as cometary nuclei) at the bottom of small craters on Ryugu. Such boulders are probably the most pristine parts of the planetesimals that formed Ryugu’s parent body and might have been captured by Hayabusa2 sampling.

Breakdown Strength of TiO 2 /Epoxy Nanocomposites Using Centrifugation Agglomerate Removal

Abstract: In this study, TiO 2 /epoxy nanocomposites are evaluated for impulse and AC breakdown strength when agglomerations of TiO 2 nanofillers are removed by centrifugation It is found that the nanocomposites with micrometric agglomerates exhibit lower breakdown strengths than that of unfilled epoxy resin However, with the removal of agglomerates larger than 05 µm for 04 vol% filler concentration, the breakdown strengths are higher than that of unfilled epoxy resin Micrometric agglomerates of TiO 2 nanoparticles behave as defects, thus lowering the breakdown strength of the nanocomposites When such agglomerates are removed prior to curing, an improvement of the breakdown strengths is observed with very low filler concentration

Wireless Sensor Network Localization Using AoA Measurements With Two-Step Error Variance-Weighted Least Squares

Abstract: We propose a novel localization method using angle-of-arrival (AoA) measurements with two-step error variance-weighted least squares (TELS). The first step is to estimate a terminal location provisionally using least squares. The second step is to estimate the terminal location using weighted least squares, with the weights for each anchor and each evaluation-function term, calculated from the error variance based on the first step. The proposed method does not require previous information on the environment while achieving high performance. The simulation results indicate that a root mean square error (RMSE) of the proposed method is superior to that of the existing hybrid received signal strength (RSS)/AoA localization methods. When 11 anchors are deployed inside a cube with edge length 15 m, and the standard deviations of measurements are small, the RMSE of the proposed method reaches about 0.34 m. It is nearly equal to that of Cramer-Rao lower bound (CRLB) on AoA.

Explainable Deep Neural Network for Design of Electric Motors

Abstract: This study presents a novel two-step optimization method that incorporates explainable neural networks into topology optimization. The deep neural network (DNN) is trained to infer the torque performance from the input image of the motor cross section. The sensitive region that has a significant influence on the average torque is extracted using gradient-weighted class activation mapping (Grad-CAM) constructed from the DNN. Then, the optimization with respect to the torque ripple is performed only in the incentive region with little influence on the average torque. The proposed method is shown to increase the average torque of an interior permanent magnet (IPM) motor by 14% and reduce the torque ripple by 79% compared with the original model.

RCS Synthesis of Array Antenna With Circulators and Phase Shifters and Measurement Method for Deterministic RCS Reduction

Abstract: This article presents a radar cross section (RCS) reduction method using antennas with circulators and phase shifters. In this method, an antenna connected to a circulator with a phase shifter and an amplifier in its circulation path is utilized, and the amplitude and phase of the antenna mode scattered field, which is the reradiated field of the antenna, are controlled to cancel out the structural mode scattered field. This article proposes array RCS synthesis methods for antenna RCS minimization and for broadening RCS reduction bandwidth and angular range. In addition, a measurement method to determine the amplitude and phase of the antenna mode of each antenna element and the structural mode of the array is proposed for deterministic RCS reduction. The effectiveness of the proposed method is confirmed experimentally in a monostatic case using an eight-element array antenna with circulators and digital phase shifters.

Millimeter-Wave GaN Devices for 5G: Massive MIMO Antenna Arrays for Sub-6-Ghz and mm-Wave Bandwidth

Abstract: Semiconductor technology plays an important role in realizing the 5G mobile communication system One of the technical objectives for 5G is to significantly boost cellular network throughput-by 100 times compared with 4G (to achieve a peak data rate of g 10 Gb/s) [1] Achieving this goal will require massive multiple input/multiple output (MIMO) antenna technology [2], [3]

Selective Gate Driving in Intelligent Power Modules

Abstract: Due to practical limitations in the manufacturing of power semiconductor dies, high power modules are composed of several dies in parallel in order to meet the desired load current requirements. With careful attention to the design, modern insulated gate bipolar transistor (IGBT)-based power modules feature relatively balanced current distribution amongst the parallel dies. However, owing to the increased switching speeds of wide bandgap devices, i.e., silicon carbide (SiC), it is challenging to design the package to achieve both low-loss and balanced operation. In this article, a technique is proposed where the individual dies in a multidie power module can be selectively driven by a closely integrated gate buffer. Amongst the benefits achieved by selectively driving the die gates, a profiling of the power loss within the intelligent power module is enabled. Furthermore, a practical technique to estimate the individual die temperatures is presented, and using the same method, the on-state voltage of the power module during load current conduction can be estimated. Finally, it is experimentally demonstrated that the combination of individual junction temperature estimation and the selective gate driving can be used to increase the power density of the power module by better utilizing the component dies.

High Output Power Density of 2DHG Diamond MOSFETs With Thick ALD-Al 2 O 3

Abstract: This article reports on the high operation voltage large-signal performance of two-dimensional hole gas diamond metal–oxide semiconductor field-effect transistors (MOSFETs) with thick atomic-layer-deposition (ALD)-Al2O3 formed on high purity polycrystalline diamond with a (110) preferential orientation. MOSFETs with a 1- $\mu \text{m}$ gate-length having a gate oxide layer of 200-nm-thick Al2O3, formed by ALD and asymmetric structures, to withstand high-voltage operations. The large-signal performances were evaluated at a quiescent drain voltage of greater than −60 V for the first time in diamond field-effect transistor (FET). As a result, an output power density of 2.5 W/mm under class-A operation at 1 GHz, which is higher than that of diamond FETs fabricated by a self-aligned gate process, was obtained. Moreover, an output power density of 1.5 W/mm was exhibited by the MOSFET when biased at a quiescent drain voltage of −40 V under class-AB operation at 3.6 GHz using an active load-pull system. This is the highest recorded value for diamond FETs at a frequency greater than 2 GHz, owing to the high-voltage operation. These results indicate that diamond p-FETs under high-voltage operations are the most suitable for high-power amplifiers with complementary circuits.

Authentic Leadership Fostering Creativity in Start-ups: Mediating Role of Work Engagement and Employee Task Proactivity:

Abstract: This study investigates the effect of authentic leadership (AL) on employee creativity and the mediating role of work engagement (WE) and employee task proactivity (ETP) in the context of start-ups...

Data-Efficient Learning for Complex and Real-Time Physical Problem Solving Using Augmented Simulation

Abstract: Humans quickly solve tasks in novel systems with complex dynamics, without requiring much interaction. While deep reinforcement learning algorithms have achieved tremendous success in many complex tasks, these algorithms need a large number of samples to learn meaningful policies. In this letter, we present a task for navigating a marble to the center of a circular maze. While this system is very intuitive and easy for humans to solve, it can be very difficult and inefficient for standard reinforcement learning algorithms to learn meaningful policies. We present a model that learns to move a marble in the complex environment within minutes of interacting with the real system. Learning consists of initializing a physics engine with parameters estimated using data from the real system. The error in the physics engine is then corrected using Gaussian process regression, which is used to model the residual between real observations and physics engine simulations. The physics engine augmented with the residual model is then used to control the marble in the maze environment using a model-predictive feedback over a receding horizon. To the best of our knowledge, this is the first time that a hybrid model consisting of a full physics engine along with a statistical function approximator has been used to control a complex physical system in real-time using nonlinear model-predictive control (NMPC).

Low-cost distance-spoofing attack on FMCW radar and its feasibility study on countermeasure

Abstract: In this paper, we present a low-cost distance-spoofing attack on a millimeter-wave frequency-modulated continuous wave (FMCW) radar. It uses only a replica radar chipset and a single compact microcontroller board in mass production. No expensive and bulky test instrument is required; hence, a low-cost and lightweight attack setup is developed. Despite the limited hardware resources used in this setup, the replica radar can be precisely synchronized with the target radar for distance spoofing. A half-chirp modulation scheme enables timing compensation between crystal oscillators on the replica and the target radar boards. A two-step delay insertion scheme precisely controls the relative delay difference between two radars at nanosecond order; consequently, the attacker can manipulate the distance measured at the target radar with only a $$\pm \,10$$ m ranging error. Moreover, the feasibility of spoofing attacks on a conventional countermeasure employing random-chirp modulation is discussed. Simulation-based experiments reveal that the attack occurs successfully by estimating the random chirp pattern. This demonstrates the potential feasibility of low-cost malicious attacks on commercial FMCW radar as a physical security threat.

Residual stress in electrical discharge coatings

Abstract: Electrical discharge coatings (EDC) can be applied on complex metal components to repair or act as protective coatings. A variant of the EDM process, it can be used to make coatings up to several mm thickness on electrically conductive substrates using sacrificial electrodes. The technology can be classified under thin EDC which is a surface modification process or thick EDC, also known by the commercial name “MSCoating”, which is a surface coating process. Inclusion of a high current pulse in the discharge waveform results in high deposition efficiencies of between 40 and 200 μm/min, with a subsequent decrease in energy into the coating per volume of material resulting in reduced re-melting of deposited material; the thermal shrinkage phenomenon seen in standard EDM recast layers is not as significant here. This results in thick EDCs with consistent tensile residual stresses of between +70 and + 100 MPa. Exclusion of the high current pulse reduces the deposition efficiency to between 0.5 and 10 μm/min. The subsequent increase in energy into the coating increases the melting and quenching of material, resulting in a more nanostructured or amorphous layer. This results in thick EDCs with largely compressive residual stresses, with a range of between +6 and −140 MPa, explained by amorphisation induced volume expansion. In cases where the deposition efficiency is sufficiently low, below 0.1 μm/min, increased melting and quenching of coating material results in high tensile residual stresses due to the thermal expansion mismatch between the layer and substrate. This results in thin EDCs with average tensile residual stresses of between +440 and +490 MPa. It is proposed that the changeable and controllable directionality of the residual stress within these coatings is a positive attribute, ultimately allowing tailorable coatings with regions of favourable residual stress dependent on final application, e.g. for wear or fatigue.

Steer-by-wire electrical power steering device, and control method therefor

Abstract: An electric power steering device of a steer-by-wire type includes: a steering input mechanism, which includes a steering wheel to be operated by a driver; a reaction force motor, which is configured to apply a steering reaction force to the steering wheel; a steering motor, which is configured to output a steering force; a steering mechanism, which is prevented from being mechanically connected to the steering input mechanism, and is configured to steer a steered wheel through the steering force generated by the steering motor; and a drive control device, which is configured to carry out drive control for the steering motor and the reaction force motor. At least one of the steering motor or the reaction force motor is constructed of a double-winding motor of a double-inverter type in which each of windings is duplexed, and the respective duplexed windings are individually driven by two inverters.

Optimized Reactive Power Capability of Wind Power Plants With Tap-Changing Transformers

Abstract: With the recent advancements in power electronics for wind turbines (WTs) and increasing penetration of wind energy, wind power plants (WPP) have become necessary contributors of reactive power support for the bulk power system. Balancing reactive power support with individual WT operating requirements in a cost-effective manner is a challenge for WPP designers. In this paper, we present a methodology to optimize the WPP reactive power capability as seen from the point of common coupling (PCC), accounting for steady-state operating capabilities of the WPP equipment. Thus, the proposed methodology determines the configuration of the tap-changing transformers within the WPP that maximizes the amount of reactive power the WPP can either consume or inject to the network, considering uncertain levels of wind power generation and voltage magnitudes at the PCC. The optimized reactive power capability (ORPC) problem is initially formulated as a mixed-integer nonlinear programming (MINLP) model. Then, a set of efficient linearization techniques are used to obtain a mixed-integer linear programming (MILP) model that can be solved via off-the-shelf mathematical programming solvers. Results demonstrate that the proposed MILP model is a scalable, flexible and accurate method to maximize the reactive power capability of WPP.

Traffic state estimation by backward moving observers: An application and validation under an incident

Abstract: This study analyzes measurements by backward moving observers that could be probe vehicles running backward on the opposite lane observing forward moving traffic to be investigated. These probe vehicles are called as backward probe vehicles (BP) and they are proven to measure the traffic flow and density. Using some advanced technology, a BP is assumed to estimate the flow of vehicles running forward from their passing time measurements along the BP trajectory. Then, as a useful application for the flow measurement by a BP, we propose a data assimilation method that estimates traffic states under an incident on an expressway section utilizing BP measurements in addition to conventional probe vehicles moving forward (forward probe vehicles) and detector data. Ample literature exists on traffic state estimation using several sensing data. However, they have difficulty in estimating traffic states during an incident, since the observations of the incident period and the declined flow rate due to the incident may not be sufficiently accurate. Therefore, this study proposes a state space model (SSM) that estimates traffic states under an incident on an expressway utilizing BP measurements. The model validation using a hypothetical network with an incident confirms the promising potential of the proposed model; that is, the reproducibility of traffic states using BP measurements is superior to one using forward probe measurements.

A Low-Complexity Probabilistic Amplitude Shaping with Short Linear Block Codes

Abstract: We propose a new probabilistic amplitude shaping (PAS) scheme based on short linear block codes. In the proposed system, the capacity-approaching signal distribution is generated in the process of decoding linear block codes for a given information bit sequence. We associate the design problem of shaping codes with the classical covering problem, suggesting the use of good covering codes for shaping. From simulation results, it is demonstrated that by selecting perfect binary codes as our shaping codes, the proposed scheme offers a shaping gain of around 0.3–1.0 dB. By comparing with the enumerative sphere shaping (ESS) of the same block length, we verify that the proposed scheme achieves significantly lower storage complexity and computational complexity at the receiver even with comparable block error rate performance.

Static Eccentricity Fault Detection for PSH-type Induction Motors Considering High-order Air Gap Permeance Harmonics

Abstract: Diagnosis of static eccentricity (SE) fault for induction motors (IMs) is essential for the quality control of the machines, especially during their manufacturing process. Principal slot harmonic (PSH) type IMs have special combinations of rotor bar number and pole pair number, and it has been shown in previous works that conventional methods cannot effectively detect SE fault for these machines. Aiming at finding an effective approach for the SE fault detection for PSH-type IMs, this paper presents an analysis of SE-induced line currents in IMs with the higher-order harmonics of the air gap permeance considered. The analysis reveals that the second-order harmonic in the air gap permeance can induce SE-level-related signals in the line current of PSH-type three-phase IMs. The generation mechanism of the signature current signal is validated by simulations with an analytical IM model and a time-stepping finite element model. The signature signal in the motor's current discussed in this paper provides a new method for quantitative detection of SE fault for PSH-type IMs.

Finite-Element Analysis for Magnetic Flux in End Region of Synchronous Machine Using End-Winding Model

Abstract: Designers of the synchronous machine are required to quickly and accurately predict its characteristics. 2-D finite-element analysis (FEA) is subject to error caused by neglecting the magnetic flux in the end region composed of the end winding and the space surrounding it. For accurate prediction using 2-D FEA, it is necessary to calculate the end inductance due to the magnetic flux of the end region and to correct the armature inductance. This article proposes a modeling method, which introduces the Neumann boundary to calculate the end inductance correctly by the partial 3-D FEA simulating only the end region, and a correction method for 2-D FEA using the end inductance. Comparison reveals that the calculated characteristics obtained from the corrected 2-D FEA are in good agreement with the measured characteristics. It is demonstrated that the end inductance given by the partial 3-D FEA has reliable accuracy and the corrected 2-D FEA can achieve the same level of accuracy as full 3-D FEA in a computation time less than 1/10.

Carrier Stored Layer Density Effect Analysis of Radiated Noise at Turn-On Switching via Gabor Wavelet Transform

Abstract: The basic IGBT structure was reported about 40 years ago and has become more complex to achieve lower losses, higher robustness, higher reliability, and cost-effectiveness. Today’s power devices are also required to improve noise characteristics corresponding to its increasing switching speed. In noise analysis based on switching waveforms, Fourier transform (FT) is often applied to estimate the causes as device structure has frequently been improved. However, the time information is implicitly deleted according to FT, and it is difficult to consider the causes by extraction of specific parts on waveforms because every waveform’s time axis includes important information for device structures. This article presents analysis methodology to identify the key parts without deleting time information by using a wavelet transform and elucidates the effect of transition of dominant radiated noise generated at turn-on operation in case of different carrier stored layer density in CSTBTs.

Field Demonstration of Real-time 14 Tb/s 220 m FSO Transmission with Class 1 Eye-safe 9-aperture Transmitter

Abstract: We demonstrated a 9-aperture transmit and single aperture receive FSO system transmitting 35-WDM 400 Gb/s DP-PS-16-QAM signals over 220 m. By splitting the WDM signals into 9 groups, eye-safe transmit power density was enabled.

Comparison of Three Feedback Modalities for Haptics Sensation in Remote Machine Manipulation

Abstract: Previous studies have verified the usefulness of visual haptics for achieving the appropriate grasping force and task success rate to operate remote machines. However, its capabilities have not been evaluated objectively and quantitatively. We comprehensively compare three feedback modalities (i.e., sound, vibration, and light) for providing pseudo-haptic information on contact with an object, which we apply to grasping an object with a remotely operated robot arm. Experimental results verify that the light modality (i.e., visual haptics) minimizes the grasping force and processing load in the operator's brain. We then develop a prototype of a remote machine to demonstrate the feasibility of visual haptic feedback. We consider three implementations (i.e., a light-emitting diode, model-based superimposition, and model-less superimposition) to verify the performance. The results show that visual haptics can stabilize the performance of delicate tasks such as grasping and carrying fragile raw eggs and potato chips. We demonstrate that our visual haptics method (i.e., superimposing haptic information as images on the contact points of the robot's fingertips) can significantly improve the operability of remote machines without the need for highly complex and expensive interfaces.

Critical Agglomerate Size for Electrical Insulation Lifetime Extension of Epoxy/TiO 2 Nanocomposite with a Void Defect

Abstract: This study investigates the time to breakdown of epoxy/TiO 2 nanocomposites with a void defect In the tests, partial discharge (PD) is continuously monitored to clarify the degradation of the nanocomposites In evaluating the dependence of the maximum agglomerate size and the volume fractions of the TiO 2 particles, it is found that the agglomerate size, rather than the volume fractions, dominates the electrical insulation lifetime of the nanocomposites Furthermore, the lifetime increases drastically when the agglomerate size exceeds a critical value The continuous PD signal monitoring reveals that the lifetime extension of the nanocomposites is achieved due to delaying the electrical tree propagation in the nanocomposite, rather than extensions of the times required for the transition from the void discharges to the tree initiation

Ku -Band 70-/30-W-Class Internally Matched GaN Power Amplifiers With Low IMD3 Over a Wide Offset Frequency Range of Up To 400 MHz

Abstract: This study describes the Ku -band 70- and 30-W-class internally matched gallium nitride (GaN) power amplifiers (PAs) for multi-carrier satellite communications (SatComs). The GaN PAs maintain low third-order intermodulation distortion (IMD3) over a wide offset frequency range of up to 400 MHz, whereas in the Ku -band, one PA can deliver a high peak output power of approximately 70 W and the other PA, a peak output power of higher than 30 W. To realize a wide offset frequency operation, our proposed output-matching circuit includes three different types of difference-frequency short circuits, two of which are embedded into a tournament-shaped output-matching circuit inside the PA package and the rest is embedded into the drain bias feed placed outside the package. To verify the short-circuit design and its effectiveness, two different power classes (70 and 30 W), Ku -band GaN PAs, were designed and fabricated, and then, their output transfer characteristics focusing on IMD3 were measured. The measurements show that the 70-W-class GaN PA achieves a peak output power of 48.6 dBm while maintaining a linear output power of over 40 dBm and an IMD3 of less than −26 dBc over wide offset frequencies ranging from 1 to 400 MHz. The 30-W-class GaN PA maintains a linear output power of over 36.3 dBm and an IMD3 of less than −27 dBc over wide offset frequencies of up to approximately 600 MHz. To the best of the authors’ knowledge, these PAs have a record output power level over a wide frequency range of 1–400 MHz or higher under the condition of a low IMD3 of less than −25 dBc, compared to previously reported Ku -band GaN PAs used for multi-carrier SatComs.