Article
Computer Science, Information Systems
Gianni Bosi, Antonio Raffo, Valeria Vadala, Rocco Giofre, Giovanni Crupi, Giorgio Vannini
Summary: In this paper, we investigate the degradation effects observed on 0.15-μm GaN HEMT devices operating under realistic power amplifier conditions through experimental methods. A low-frequency load-pull characterization technique is utilized to apply power amplifier conditions to the devices under test (DUT), providing information consistent with RF operation. The experiments are conducted at different temperatures and compare the degradation effects under different power amplifier operations.
Article
Computer Science, Information Systems
Lin Peng, Jianqiang Chen, Zhihao Zhang, Gary Zhang
Summary: A compact GaN MMIC power amplifier with dimensions of 1.94 x 0.83 mm(2) is designed for 5G millimeter-wave communication, achieving high output power, gain, and efficiency at 27 GHz. The broadband matching networks are based on load-pull analysis and Chebyshev filter synthesis theory, providing stable output power and gain across 24-30 GHz.
Article
Computer Science, Information Systems
Mohammad Shahmoradi, Sayyed-Hossein Javid-Hosseini, Vahid Nayyeri, Rocco Giofre, Paolo Colantonio
Summary: This paper presents a novel and accurate procedure for designing a Doherty power amplifier (DPA) for wireless systems. The method involves a systematic approach to designing the matching networks of both Main and Auxiliary devices, and utilizes an optimization process to ensure their input impedance falls within the optimal regions obtained from load- and source-pull simulations. In addition, the paper proposes a method to accurately account for the loading effect of the Auxiliary amplifier on the Main one at back-off when designing the Main PA. Experimental results demonstrate the effectiveness of the proposed method.
Article
Engineering, Electrical & Electronic
Chengcheng Xie, Gang Yu, Ziheng Zhang, Huanpeng Wang, Youda Li, Yunqiu Wu, Yunchuan Guo, Ruimin Xu, Yuehang Xu
Summary: This paper introduces a simplified polynomial behavioral model which accurately predicts the forward and reverse propagating waves when a microwave amplifier is cascaded with other components. Experimental results verify the reliability and effectiveness of the model in cascade simulation.
MICROWAVE AND OPTICAL TECHNOLOGY LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Peng Chen, Rui-Jia Liu, Luqi Yu, Ziming Zhao, Xiao-Wei Zhu, Debin Hou, Jixin Chen, Chao Yu, Wei Hong
Summary: This article proposes a simplified method to emulate the active load modulation between the carrier and peaking transistors in a Doherty power amplifier (DPA) design based on large-signal simulations. The proposed method considers the nonlinear interaction between the load-modulated transistors, providing the advantages of predicting their real-world performance and synthesizing optimum load-modulation trajectories in a DPA design. The measured results of a designed mmWave GaN MMIC DPA show high power-added efficiency, saturated output power, and low adjacent channel power ratio levels when tested with a modulated signal using digital predistortion.
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES
(2023)
Article
Computer Science, Information Systems
Veli-Pekka Kutinlahti, Anu Lehtovuori, Ville Viikari
Summary: This paper studies the effect of load-pull on the 3rd order intermodulation (IM3) radiation characteristics of a transmitting active phased array, and introduces a general model for predicting the spatial distribution of fundamental tones and intermodulation products. The data used comes from a load pull measured amplifier prototype and a simulated linear antenna array, which are co-simulated for system behavior. The system is optimized for maximum main tone beam powers and a signal-to-IM3 ratio (SI3R) of 40 dB. The study shows that the load-pull system model improves SI3R by an average of 10.4 dB compared to traditional small-signal modeling, while only decreasing the main beam power densities by 0.3 dB compared to traditional small-signal modeling. Optimizing for SI3R degrades beam pattern by increasing beamwidths and decreasing sidelobe levels (SLL).
Article
Computer Science, Hardware & Architecture
Meilin Wu, Shijie Wang, Chao Yu, Giovanni Crupi, Jialin Cai
Summary: This work presents the design of a load-modulated balanced power amplifier (LMBA) based on the X-parameter model. A 10-W GaN packaged transistor is used for the power amplifier design. The X-parameter model accurately predicts the nonlinear behavior of the device and determines the optimal output power and drain efficiency region for the LMBA design. An LMBA is fabricated and tested, showing good performance with high output power and efficiency.
IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS
(2023)
Review
Public, Environmental & Occupational Health
Sudip Bhattacharya, Petra Heidler, Saurabh Varshney
Summary: Poor nations are facing the burden of both communicable and non-communicable diseases, with neglected non-communicable diseases becoming a major public health challenge. The BIG FOUR NCDs, including diabetes, cancer, chronic respiratory diseases, and cardiovascular diseases, are recognized as the main contributors to global health loss. However, other NCDs are often neglected despite accounting for a significant portion of the global burden of NCDs. This paper briefly discusses the disease burden of some significant yet neglected NCDs.
FRONTIERS IN PUBLIC HEALTH
(2023)
Article
Chemistry, Analytical
Lin Peng, Jing Yan, Zhihao Zhang, Gary Zhang
Summary: This paper presents a compact GaN microwave monolithic integrated circuit driver amplifier (MMIC DA) for 5G millimeter-wave communication. The design process involves determining the optimal impedance domain, extracting the nonlinear output capacitance and input impedance response of the stabilized transistor, and constructing filter-based synthesized matching networks using the Chebyshev impedance transformer. The measured results demonstrate high saturated output power, low fluctuation, and good power-added efficiency.
Article
Computer Science, Information Systems
Lin Peng, Zhihao Zhang, Gary Zhang
Summary: This paper presents the design procedure of a compact and efficient monolithic microwave integrated circuit power amplifier (MMIC PA) for 5G millimeter-wave communication using a 0.1 μm GaN-on-Si process. Load/source-pull simulations were conducted to create accurate matching models and determine the optimal impedance domain. The design incorporates miniature size, explicit formulas, and numerical optimization to synthesize matching networks for the input and output stages, resulting in high performance over a wide frequency range.
Article
Computer Science, Information Systems
Dae-Woong Park, Dzuhri Radityo Utomo, Byeonghun Yun, Hafiz Usman Mahmood, Sang-Gug Lee
Summary: This paper proposes a technique for simultaneous output power- and gain-matching in a sub-THz power amplifier design and presents the implementation of a 150 GHz single-ended two-stage PA in a 65-nm CMOS process based on this technique. The proposed technique maximizes small-signal power gain and large-signal output power, leading to improved performance metrics of the amplifier.
Article
Engineering, Electrical & Electronic
Su Jiangtao, Cai Jialing, Zheng Xing, Sun Lingling
Summary: This article introduces a fast real-time two-tone active load-pull algorithm to evaluate the nonlinear performance of RF devices in wireless systems. The algorithm extracts a nonlinear behavior model using real-time measurement data, and predicts the injected signal value in the active load-pull system, improving the measurement speed.
CHINESE JOURNAL OF ELECTRONICS
(2022)
Article
Materials Science, Multidisciplinary
Michal Koci, Ondrej Szabo, Gabriel Vanko, Miroslav Husak, Alexander Kromka
Summary: The nanocrystalline diamond (NCD) film is a promising material for various sensing applications due to its unique combination of physical, chemical, and optoelectronic properties. In this study, the surface of NCD was modified using different methods, such as variation in layer morphology, surface termination (H-NCD and O-NCD), and the addition of Au nanoparticles (Au NPs). The properties of each modified structure were measured, compared, and evaluated. The gas response of the modified NCD films was tested using oxidizing gas NO2 and reducing gas NH3, and the electrical properties were measured in a temperature range from 22 degrees C to 125 degrees C.
DIAMOND AND RELATED MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Lu-Chuan Zhang, Long-Xing Shi
Summary: This article presents a novel design of a Class-F monolithic microwave integrated circuit (MMIC) power amplifier (PA) operating at L-band with a power-added-efficiency (PAE) better than 70%. Through the use of load/source-pull techniques and LC resonators, the design achieves optimal impedances at fundamental and harmonic frequencies, resulting in highly efficient performance.
MICROWAVE AND OPTICAL TECHNOLOGY LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Jose A. Garcia, M. Nieves Ruiz, Ana Cordero, David Vegas
Summary: A novel architecture for a two-way outphasing power amplifier was proposed to extend the power coverage significantly by introducing an external signal, utilizing a load-modulation strategy to achieve high efficiency. In tests, the amplifier demonstrated remarkable efficiency and low power back off values at different output power levels, showing capability to handle high peak-to-average power ratio signals and adjacent channel leakage issues.
IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
A. El-Helou, Y. Cui, M. J. Tadjer, T. J. Anderson, D. Francis, T. Feygelson, B. Pate, K. D. Hobart, P. E. Raad
Summary: The study presents full thermal characterization of GaN power devices with different substrates to manage performance-limiting self-heating by utilizing an innovative reverse modeling approach. It compares the thermal properties of HEMTs on Si, SiC, and Diamond substrates and provides conclusions to guide further developments in GaN HEMT thermal management strategies.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2021)
Article
Nanoscience & Nanotechnology
Andrew C. Lang, D. Scott Katzer, Neeraj Nepal, David J. Meyer, Rhonda M. Stroud
Summary: Epitaxial transition metal nitrides (TMNs) are a new class of crystalline thin film metals that can be integrated with common group III-nitride semiconductors. This study used high-resolution transmission electron microscopy to identify different phases of tantalum nitrides with N-sublattice ordering, revealing Ta-deficient films with specific planar defects. These findings lay the foundation for the application of this epitaxial TMN material in new electronic and superconducting device structures.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Multidisciplinary Sciences
Phillip Dang, Guru Khalsa, Celesta S. Chang, D. Scott Katzer, Neeraj Nepal, Brian P. Downey, Virginia D. Wheeler, Alexey Sus, Andy Xie, Edward Beam, Yu Cao, Cathy Lee, David A. Muller, Huili Grace Xing, David J. Meyer, Debdeep Jena
Summary: Researchers have successfully observed the integer quantum Hall effect in a two-dimensional electron gas by combining high critical temperature nitride superconductors with nitride semiconductor heterostructures of metal polarity.
Article
Chemistry, Physical
Anand B. Puthirath, Eliezer F. Oliveira, Guanhui Gao, Nithya Chakingal, Harikishan Kannan, Chenxi Li, Xiang Zhang, Abhijit Biswas, Mahesh R. Neupane, Bradford B. Pate, Dmitry A. Ruzmetov, A. Glen Birdwell, Tony G. Ivanov, Douglas S. Galvao, Robert Vajtai, Pulickel M. Ajayan
Summary: The study found that Hummer's method is very effective in oxidizing pristine diamond surfaces, especially in the presence of strong oxidizing agents. Microcrystalline diamond powder is more prone to oxidation to polycrystalline diamond wafers.
CHEMISTRY OF MATERIALS
(2021)
Article
Engineering, Environmental
William A. Maza, Vanessa M. Breslin, Jeffrey C. Owrutsky, Bradford B. Pate, Albert Epshteyn
Summary: This study investigates the rate constants and activation energies associated with the reduction of linear perfluoroalkyl carboxylates and perfluoroalkyl sulfonates by hydrated electrons. The results show that the reduction process is diffusion-controlled with no significant differences in activation energies between the two surfactants, despite slightly different rate constants observed.
ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS
(2021)
Article
Engineering, Environmental
William A. Maza, Brian D. Etz, Timothy C. Schutt, Brian L. Chaloux, Vanessa M. Breslin, Bradford B. Pate, Manoj K. Shukla, Jeffrey C. Owrutsky, Albert Epshteyn
Summary: Disagreements persist regarding the rate constants for the initial reduction of perfluorooctanoate (PFOA) by the hydrated electron, eaq-. In this study, a nonlinear dependence of the eaq- decay rate on the PFOA concentration is demonstrated, which is attributed to the aggregation of PFOA below the critical micellar concentration. A kinetic model is proposed to explain the reaction between PFOA and eaq- at low concentrations, and the model adequately fits the experimental data. The results suggest that the aggregation of PFOA decreases the probability of its reduction by eaq-.
ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS
(2022)
Article
Materials Science, Multidisciplinary
David F. Storm, Sergey Maximenko, Andrew C. Lang, Neeraj Nepal, Tatyana Feygelson, Bradford B. Pate, Chaffra A. Affouda, David J. Meyer
Summary: Trace amounts of Mg deposited on a diamond (100) substrate surface assist in the growth of cubic boron nitride (c-BN) through ion beam-assisted molecular beam epitaxy. Films grown with Mg exhibit primarily cubic structures, with a high density of stacking faults and twinning observed in high-resolution scanning transmission electron microscopy.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2022)
Article
Physics, Applied
Diego Vaca, Matthew Barry, Luke Yates, Neeraj Nepal, D. Scott Katzer, Brian P. Downey, Virginia Wheeler, Luke Nyakiti, David J. Meyer, Samuel Graham, Satish Kumar
Summary: In this study, we investigate the lower thermal conductivity of beta-Ga2O3 thin films grown by MBE. We compare experimental results with numerical predictions and find that the presence of boundary scattering and defects significantly affect the thermal conductivity of the thin films. By considering various types of defects in the calculations, we identify that crystals with gallium vacancies and stacking faults exhibit thermal conductivities closer to the experimental values. These findings provide insights for improving the thermal conductivity of MBE-grown samples.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Vikrant J. Gokhale, Matthew T. Hardy, D. Scott Katzer, Brian P. Downey
Summary: This letter presents the first demonstration of epitaxial scandium aluminum nitride (ScAlN) based high-overtone bulk acoustic resonators (epi-HBARs) with over 1600 acoustic cavity resonance modes spanning the X - Ka bands (8 GHz - 40 GHz). Key metrics for the ScAlN epi-HBARs include Q > 7000, fxQ > 10(14) Hz, and k(eff)(2) xQ(BVD) > 0.22 at cryogenic temperatures for frequencies as high as 40 GHz (>500, >6 x 10(12) Hz, >0.1 at room temperature). Such robust RF MEMS epi-HBARs with piezoelectric drive and readout are promising candidates for compact microwave/millimeter wave signal processing elements.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Brian P. Downey, Shawn Mack, Andy Xie, D. Scott Katzer, Andrew C. Lang, James G. Champlain, Yu Cao, Neeraj Nepal, Tyler A. Growden, Vikrant J. Gokhale, Matthew T. Hardy, Edward Beam, Cathy Lee, David J. Meyer
Summary: In this study, the micro-transfer printing technique is used to integrate two solid-state RF device technologies, GaN and GaAs high-electron-mobility transistors, on the same interposer. The devices are released from their growth substrate using an epitaxial sacrificial layer, and a thin polymer adhesion layer is used to ensure a strong bond with the target substrate. The results show that the device/interposer interface has no voids, and the polymer adhesion layer has a thickness of 5+/-2 nm. There is no significant degradation in dc electrical characteristics after device transfer for either device technology. The ability to combine different solid-state technologies at the device level with high density offers a promising approach for meeting the demands of next-generation RF and mixed-signal circuits.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Materials Science, Coatings & Films
Neeraj Nepal, D. Scott Katzer, Andrew C. Lang, Brian P. Downey, Matthew T. Hardy, David J. Meyer
Summary: Tantalum nitride (γ-Ta2N) thin films were grown on 3 in. diameter 6H- or 4H-SiC substrates by radiofrequency plasma molecular beam epitaxy (MBE). The MBE grown layers showed epitaxial characteristics and nearly pure γ-Ta2N phase. The lattice parameters and strain of the films on SiC were measured. Additionally, the MBE growth of AlN/γ-Ta2N /SiC heterostructures was demonstrated.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Acoustics
Vikrant J. Gokhale, Albrecht Jander, Brian P. Downey, Pallavi Dhagat, Shawn C. Mack, D. Scott Katzer, Jason A. Roussos, David J. Meyer
Summary: This study presents a detailed characterization and analysis of magnetoelastic high-overtone bulk acoustic resonators (ME-HBARs) operating in the S-band. These devices are fabricated by microtransfer printing piezoelectric GaN transducers onto a ferrimagnetic YIG substrate. The experiment demonstrates the hybridization of phonons and magnons in YIG, allowing for the suppression or tuning of acoustic modes in the ME-HBAR. The ME-HBARs can be used as dynamically tunable or switchable resonators, oscillators, comb filters, and frequency selective limiters in RF signal processing subcomponents.
IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL
(2023)
Article
Physics, Applied
Eric N. Jin, Andrew C. Lang, Brian P. Downey, Vikrant J. Gokhale, Matthew T. Hardy, Neeraj Nepal, D. Scott Katzer, Virginia D. Wheeler
Summary: This work demonstrates the growth of SrTiO3 thin films on high-electron-mobility transistor heterostructures based on an emergent ultra-wide bandgap (UWBG) semiconductor ScAlN, and investigates the effects of pre-growth chemical treatments on the heterostructure properties. It is found that among the treatments studied, the solvent and sulfuric-phosphoric acid cleans have the least disruptive effects on the electrical properties of the GaN channel, while the sulfuric-phosphoric acid clean results in the best oxide crystallinity. The transmission electron microscopy imaging reveals that intermixing occurs at the oxide-nitride interfaces for both samples, but the sample treated with sulfuric-phosphoric acid has lower interface roughness and larger STO grain size.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Matthew T. Hardy, Andrew C. Lang, Eric N. Jin, Neeraj Nepal, Brian P. Downey, Vikrant J. Gokhale, D. Scott Katzer, Virginia D. Wheeler
Summary: This work investigates the role of nucleation layer, growth temperature, and strain management in maximizing the material properties of high ScN fraction ScxAl1-xN on SiC substrates. The study finds that optimizing these factors can improve the crystal quality and defect density of ScxAl1-xN material, making it suitable for applications in RF resonators, filters, and ferroelectric devices.
JOURNAL OF APPLIED PHYSICS
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Vikrant J. Gokhale, Brian P. Downey, D. Scott Katzer, David J. Meyer
Summary: This study investigates the phonon diffraction limited performance of GaN/AIN/NbN/SiC epitaxial HBARs and explores the tradeoffs in using them compared to confocal HBARs with curved engineered surfaces. The smallest epi-HBARs achieve high performance near the diffraction limit at 7.2K, while larger devices not limited by diffraction exhibit even higher performance.
2021 34TH IEEE INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS (MEMS 2021)
(2021)
