Search Results (24)

This paper presents the design and implementation of an ultra-wideband (UWB) and flat gain low noise amplifier (LNA) using 0.15 µm GaAs pHEMT technology, specifically tailored for applications that benefit from multi-band capability, such as satellite communication. The designed LNA consists of three stages: Two stages are cascoded using source degeneration with a resistor for low noise and high linearity, and the third cascaded stage is utilized for high gain. The designed UWB LNA exhibits a measured gain of 17.4 ± 1 dB between 312 and GHz and a 3 dB bandwidth of 12.4 GHz (1.6–14 GHz). It achieves a noise figure (NF) of 2.5–4.3 dB and an output P1dB of 15 dBm. The chip size is $3\times 1$${\mathrm{mm}}^2$, and it operates without the need for any external components. When compared to LNAs in the literature, the proposed design stands out for its flat gain in the specified frequency band, making the LNA particularly attractive for volume-limited and power-constrained applications. Full article

This paper presents a 17–38 GHz wideband low-noise amplifier (LNA) designed in a 150-nm GaAs pHEMT process. The proposed amplifier adopts a cascode topology with an interstage inductor between the common-source (CS) and common-gate (CG) stages, and a series inductor at the source node of the CS stage for source degeneration. By incorporating these inductors in the amplification stage, simultaneous noise and input matching is facilitated, while achieving flat gain characteristics over a broad frequency range and ensuring stability. In addition, the amplification stage with inductors achieves input matching using only a shunt component in the DC bias path, without any series matching elements. This approach allows the amplifier to achieve simultaneous noise and input matching (SNIM), ensuring low-noise performance over a wide bandwidth. The simulation results show a flat gain of 20–23 dB and a low noise figure of 1.1–2.1 dB over the 17–38 GHz band. Full article

Proton and heavy ion irradiation experiments were carried out on Cascode GaN HEMT devices. Results show that device degradation from heavy ion irradiation is more significant than from proton irradiation. Under proton irradiation, obvious device degradation occurred. Low-frequency noise testing revealed a notable increase in internal defect density, reducing channel carrier concentration and mobility, and causing electrical performance degradation. Under heavy ion irradiation, devices suffered from single-event burnout (SEB) and exhibited increased leakage current. Failure analysis of post-irradiation devices showed that those with leakage current increase had conductive channels without morphological changes, while burned out devices showed obvious damage between the gate and drain regions. SRIM simulation indicated that ionization energy loss-induced electron–hole pairs and displacement damage from nuclear energy loss were the main causes of degradation. Sentaurus TCAD simulation of heavy ion irradiated GaN HEMT devices confirmed the mechanisms of leakage current increase and SEB. Full article

A series of problems, such as material damage and charge trap, can be caused when GaN HEMT power devices are subjected to high field stress in the off-state. The reliability of GaN HEMT power devices affects the safe operation of the entire power electronic system and seriously threatens the stability of the equipment. Therefore, it is particularly important to study the damage mechanism of GaN HEMT power devices under high field conditions. This work studies the degradation of Cascode GaN HEMT power devices under off-state high-field stress and analyzes the related damage mechanism. It is found that the high field stress in the off-state will generate a positive charge trap in the oxide layer of the MOS device in the cascade structure. Moreover, defects occur in the barrier layer and buffer layer of GaN HEMT devices, and the threshold voltage of Cascode GaN HEMT power devices is negatively shifted, and the transconductance is reduced. This study provides an important theoretical basis for the reliability of GaN HEMT power devices in complex and harsh environments. Full article

GaN HEMTs based on polarization super junction (PSJ) technology offer significant improvements in efficiency and power density over conventional silicon (Si) devices due to their excellent material characteristics, which enable fast switching edges and lower specific on-resistance. However, due to the presence of an uninterrupted channel between drain and source at zero gate bias, these devices have normally-on characteristics. In this paper, the performance of a 1200 V GaN FET utilizing PSJ technology in cascode configuration is reported. The device working principle, characteristics, and switching behavior are experimentally demonstrated. The results show that cascoded GaN FETs utilizing the PSJ concept are highly promising for power device applications. Full article

This paper will evaluate the surge current robustness of different devices in relation to the active short circuit (ASC). For the purposes of this study, a Si IGBT and its diode, two SiC MOSFETs with different voltage ratings, a SiC JFET, and three GaN HEMTs will be compared. For the GaN devices, a eMode, a dMode, and a cascode device are employed. With the exception of the Si diode, all devices exhibited a current saturation effect. This saturation will result in significant losses and, ultimately, a thermal defect. For all devices, a safe operating area (SOA) criterion is established. For the SiC and GaN devices, the saturation voltage can be employed to define the safe operating area (SOA) criterion. In this context, two on-state resistance models will be defined for these devices. One is solely temperature-dependent, while the other also considers current saturation. Consequently, the saturation voltage and the on-resistance model represent a straightforward methodology for evaluating the ASC robustness of the devices. For all devices, a recommendation for a loss model and SOA criterion will be provided. Finally, the surge current robustness of all devices is compared. The Si, SiC and GaN devices exhibit comparable high surge current robustness in the application, with the exception of the GaN eMode, which is susceptible to strong current saturation. Full article

GaN HEMT devices are sensitive to the single event effect (SEE) caused by heavy ions, and their reliability affects the safe use of space equipment. In this work, a Ge ion (LET = 37 MeV·cm²/mg) and Bi ion (LET = 98 MeV·cm²/mg) were used to irradiate Cascode GaN power devices by heavy ion accelerator experimental device. The differences of SEE under three conditions: pre-applied electrical stress, different LET values, and gate voltages are studied, and the related damage mechanism is discussed. The experimental results show that the pre-application of electrical stress before radiation leads to an electron de-trapping effect, generating defects within the GaN device. These defects will assist in charge collection so that the drain leakage current of the device will be enhanced. The higher the LET value, the more electron–hole pairs are ionized. Therefore, the charge collected by the drain increases, and the burn-out voltage advances. In the off state, the more negative the gate voltage, the higher the drain voltage of the GaN HEMT device, and the more serious the back-channel effect. This study provides an important theoretical basis for the reliability of GaN power devices in radiation environments. Full article

GaN devices are nowadays attracting global attention due to their outstanding performance in high voltage, high frequency, and anti-radiation ability. Research on total ionizing dose and annealing effects on E-mode GaN Cascode devices has been carried out. The Cascode device consists of a low-voltage MOSFET and a high-voltage depletion-mode GaN MISHEMT. Cascode devices of both conventional processed MOSFET and radiation-hardened MOSFET devices are fabricated to observe the TID effects. Experiment results indicate that, for the Cascode device with conventional processed MOSFET, the V_TH shifts to negative values at 100 krad(Si). For the Cascode device with radiation-hardened MOSFET, the V_TH shifts by −0.5 V at 100 krad(Si), while shifts to negative values are 500 krad(Si). The annealing process, after the TID experiment, shows that it can release trapped charges and help V_TH recover. On one hand, the V_TH shift and recover trends are similar to those of a single MOSFET device, suggesting that the MOSFET is the vulnerable part in the Cascode which determines the anti-TID ability of the device. On the other hand, the V_TH shift amount of the Cascode device is much larger than that of a previously reported p-GaN HEMT device, indicating that GaN material shows a better anti-TID ability than Si. Full article

This paper presents a 250 kHz bidirectional battery charger circuit using a GaN HEMT. The charger is subjected to a high-/low-side constant voltage at 200 V/20 V. The charger circuit is a hybrid of the LLC and flyback circuit topologies. Both the power output analysis and efficiency control of this circuit are simplified when the magnetization current is minimized using the low-resistance GaN HEMT. The switching frequency is controlled to match the series resonance in a way that is analogous to conventional LLC circuit controls, while the duty ratio that determines the power output and the dead time, which determines the zero voltage switching, is controlled in an analogous manner to the flyback circuit control. The charging and discharging modes were altered by applying a double-throw relay that changes the transformer turn ratio, which is different from conventional LLC designs using the switching frequency adjustment. A nominal turn ratio with N_p = 35 and N_s = 3.5 for a 200 V/20 V converter can only produce an internal series resonance with no current flowing in any charging direction. The proposed circuit using a transformer with multiple windings (N_p = 35, N_s,F = 4, and N_s,R = 3) was fabricated to deliver 125 W output power from the power grid battery to the vehicle battery in the forward (charging) mode and 90 W in the reverse (discharging) mode. The conversion efficiency was calculated to be as high as 97% in the forward mode and 95% in the reverse mode. The high conversion efficiency is due to the characteristics of the GaN HEMT, including low resistive and switching losses. The equations derived in this paper associate these losses with the series resonant frequency and power conversion rate, which highlight the advantages of using a GaN HEMT in this CLLC design. Full article

The threshold voltage instability in p-GaN gate high electron mobility transistors (HEMTs) has been brought into evidence in recent years. It can lead to reliability issues in switching applications, and it can be followed by other degradation mechanisms. In this paper, a $V_{th}$ measurement protocol established for SiC MOSFETs is applied to GaN HEMTs: the triple sense protocol, which uses voltage bias to precondition the transistor gate. It has been experimentally verified that the proposed protocol increased the stability of the $V_{th}$ measurement, even for measurements following degrading voltage bias stress on both drain and gate. Full article

This review explores the performance and reliability of power semiconductor devices required to enable the electrification of heavy goods vehicles (HGVs). HGV electrification can be implemented using (i) batteries charged with ultra-rapid DC charging (350 kW and above); (ii) road electrification with overhead catenaries supplying power through a pantograph to the HGV powertrain; (iii) hydrogen supplying power to the powertrain through a fuel cell; (iv) any combination of the first three technologies. At the heart of the HGV powertrain is the power converter implemented through power semiconductor devices. Given that the HGV powertrain is rated typically between 500 kW and 1 MW, power devices with voltage ratings between 650 V and 1200 V are required for the off-board/on-board charger’s rectifier and DC-DC converter as well as the powertrain DC-AC traction inverter. The power devices available for HGV electrification at 650 V and 1.2 kV levels are SiC planar MOSFETs, SiC Trench MOSFETs, silicon super-junction MOSFETs, SiC Cascode JFETs, GaN HEMTs, GaN Cascode HEMTs and silicon IGBTs. The MOSFETs can be implemented with anti-parallel SiC Schottky diodes or can rely on their body diodes for third quadrant operation. This review examines the various power semiconductor technologies in terms of losses, electrothermal ruggedness under short circuits, avalanche ruggedness, body diode and conduction performance. Full article

High-electron-mobility transistors based on gallium nitride technology are the most recently developed power electronics devices involved in power electronics applications. This article critically overviews the advantages and drawbacks of these enhanced, wide-bandgap devices compared with the silicon and silicon carbide MOSFETs used in power converters. High-voltage and low-voltage device applications are discussed to indicate the most suitable area of use for these innovative power switches and to provide perspective for the future. A general survey on the applications of gallium nitride technology in DC-DC and DC-AC converters is carried out, considering the improvements and the issues expected for the higher switching transient speed achievable. Full article

With the increase in renewable energy generation, microgrid has put forward higher requirements on the power density and performance of the photovoltaic inverter. In this paper, the dynamic process of inverter based on the cascode Gallium nitride (GaN) high electron mobility transistor (HEMT) for the photovoltaic (PV) application is analyzed in detail. The parasitic inductors and capacitors have been considered in our proposed equivalent model, which can explain the phenomenon that the crossover time of the voltage and current is prolonged by the parasitic parameters. The influence of the parasitic parameters is identified through theoretical analysis. By analyzing the influence of parasitic parameters, the design process of high-frequency inverter can be optimized. A 500 W inverter based on the cascode GaN HEMT is built, and the correctness of theoretical and simulation analysis is verified by the experimental results. Full article

This paper studies the synergistic effect of total ionizing dose (TID) and displacement damage dose (DDD) in enhancement-mode GaN high electron mobility transistor (HEMT) based on the p-GaN gate and cascode structure using neutron and ⁶⁰Co gamma-ray irradiation. The results show that when the accumulated gamma-ray doses are up to 800k rad(Si), the leakage-current degradations of the two types of GaN HEMTs with 14 MeV neutron irradiation of 1.3 × 10¹² n/cm² and 3 × 10¹² n/cm² exhibit a lower degradation than the sum of the two separated effects. However, the threshold voltage shifts of the cascode structure GaN HEMT show a higher degradation when exposed to both TID and DDD effects. Moreover, the failure mechanisms of the synergistic effect in GaN HEMT are investigated using the scanning electron microscopy technique. It is shown that for the p-GaNHEMT, the increase in channel resistance and the degradation of two-dimensional electron gas mobility caused by neutron irradiation suppresses the increase in the TID leakage current. For the cascode structure HEMT, the neutron radiation-generated defects in the oxide layer of the metal–oxide–semiconductor field-effect transistor might capture holes induced by gamma-ray irradiation, resulting in a further increase in the number of trapped charges in the oxide layer. Full article

Three millimeter-wave (mm-Wave) power amplifiers (PAs) that cover the key 5G FR2 band of 24.25 to 43.5 GHz are designed in two different state-of-the-art device technologies and are presented in this work. First, a single-ended broadband PA that employs a third-order input matching network is designed in a 40 nm GaN/SiC HEMT (High Electron Mobility Transistor) technology. Good agreement between the measurement and post-layout parasitic extracted (PEX) electromagnetic (EM) simulation data is observed, and it achieves a measured 3-dB BW (bandwidth) of 18.0–40.3 GHz and >20% maximum PAE (power-added-efficiency) across the entire 20–44 GHz band. Expanding upon this measured design, a differential broadband GaN PA that utilizes neutralization capacitors is designed, laid out, and EM simulated. Simulation results indicate that this PA achieves 3-dB BW 20.1–44.3 GHz and maximum PAE > 23% across this range. Finally, a broadband mm-Wave differential CMOS PA using a cascode topology with RC feedback and neutralization capacitors is designed in a 22 nm FD-SOI (fully depleted silicon-on-insulator) CMOS technology. This PA achieves an outstanding measured 3-dB BW of 19.1–46.5 GHz and >12.5% maximum PAE across the entire frequency band. This CMOS PA as well as the single-ended GaN PA are tested with 256-QAM-modulated 5G NR signals with an instantaneous signal BW of 50/100/400/9 × 100 MHz at a PAPR (peak-to-average-power ratio) of 8 dB. The data exhibit impressive linearity vs. P_OUT trade-off and useful insights on CMOS vs. GaN PA linearity degradation against an increasing BW for potential mm-Wave 5G applications. Full article