Publications by Armin Jafari | EPFL Graph Search

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The broad applications of ultrawide-band signals and terahertz waves in quantum measurements, imaging and sensing techniques, advanced biological treatments, and very-high-data-rate communications have drawn extensive attention to ultrafast electronics. In ...

The emergence of wide-band-gap (WBG) power transistors with low conduction losses and high-speed switching speeds has paved the way for more-than-ever efficient power electronics systems and huge energy saving potentials. Likewise, power density- the ratio ...

High-frequency switching is favorable for fast transient response, small size of passive components and superior power density, especially in soft-switching topologies. At high frequencies, power dissipation due to consecutive charging/discharging of gate ...

In this paper, we review some of the main methods to characterize on-state and off-state losses in wide-band-gap devices under switching conditions. In the off-state, we will discuss about losses related to charging and discharging the output capacitance i ...

In this work, we demonstrate a state-of-the-art high step-up/down dual-active-bridge (DAB) converter designed with GaN transistors, to achieve a high efficiency and large power-density. A quasi-planar matrix transformer with high step-up/down ratio is demo ...

Low ON-resistance of advanced superjunction (SJ) and GaN-on-Si transistors is of great importance in power converters, however, the anomalous loss in their output capacitance (C OSS ) severely limits their performance. In this work, we use an energy-orient ...

GaN-on-Si high-electron-mobility transistors (HEMTs) exhibit excellent properties for efficient power conversion. Nevertheless, a considerable energy loss associated with the charging and discharging of the output capacitance (COSS) in these transistors se ...

Wide-band-gap (WBG) power semiconductor devices are gaining an increasing interest in power circuits, as they exhibit a low specific ON-resistance (RON) while providing a high blocking voltage. The energy dissipation corresponding to resonantly charging an ...

For certain field-effect transistors (FETs) in soft-switching operation, the large-signal behavior of their output capacitance ( Co ) has shown to deviate considerably from the datasheet values. This can have a significant effect on hard-switching losses i ...

Wide-band-gap technologies enable ultra-high efficiencies in high-frequency power conversion. However, inadequate accuracies in electrical measurements could lead to spurious efficiency measurements, even above 100%. Furthermore, bandwidth limitations, par ...

Plasma formation in micro- and nano-scales enables an ultrahigh-dv/dt picosecond switching in an integrated circuit form factor. Such on-chip plasma devices could provide a transformative approach to achieving high-power levels at very high frequencies, fa ...

Laterally gated transistors have been proposed as an innovative device architecture in which a semiconducting channel is controlled by side gates. In this sense, the gate can either be in contact with the sidewalls or be separated by a gap. In the latter c ...

The dissipated energy (Ediss) related to the resonant charging/discharging of a transistor output capacitance, becomes a dominant loss factor for power converters operating in the MHz range. A recent work has introduced a small-signal measurement method to ...

Wide-Band-Gap semiconductors have enabled considerable miniaturization of power devices, which requires, however, new thermal management solutions to handle the resulting high heat fluxes. Recently, embedded liquid cooling in GaN-on-Si devices was demonstr ...

Recent research has reported an undesirable OFF-state loss in high-frequency soft-switching power converters, such as resonant converters. This loss is attributed to a hysteresis loss related to the charging-discharging process of the output capacitance of ...

Soft switching in dual-active-bridge (DAB) converters enables their efficient operation at high frequencies, where the reduction in the size of magnetic components could result in ultra-high power densities. Nonetheless, losing soft-switching at high frequ ...

The low ON-resistance of wide-band-gap (WBG) transistors is a key feature for efficient power converters, however, the anomalous loss in their output capacitance (COSS) severely limits their performance at high switching frequencies. Characterizing COSS-lo ...

Soft-switching power converters based on wide-band-gap (WBG) transistors offer superior efficiency and power density advantages. However, at high frequencies, loss behavior varies significantly between different WBG technologies. This includes losses relat ...

Armin Jafari

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Nanoplasma-enabled picosecond switches for ultrafast electronics

Pushing the Limits of Efficiency and Power Density in High-Frequency Power Conversion Based on Wide-Band-Gap Technologies

Small-Signal Approach for Precise Evaluation of Gate Losses in Soft-Switched Wide-Band-Gap Transistors

Switching losses in power devices: From dynamic on resistance to output capacitance hysteresis

97.4%-Efficient All-GaN Dual-Active-Bridge Converter with High Step-up High-Frequency Matrix Transformer

Investigation on Output Capacitance Losses in Superjunction and GaN-on-Si Power Transistors

Resonances on GaN-on-Si Epitaxies: A Source of Output Capacitance Losses in Power HEMTs

Output Capacitance Losses in Wide-Band-Gap Transistors: A Small-Signal Modeling Approach

Hard-Switching Losses in Power FETs: The Role of Output Capacitance

High-Accuracy Calibration-Free Calorimeter for the Measurement of Low Power Losses

Calibration-Free Calorimeter for Sensitive Loss Measurements: Case of High-Frequency Inductors

Kilowatt-range Picosecond Switching Based on Microplasma Devices

Comparison of Wide-Band-Gap Technologies for Soft-Switching Losses at High Frequencies (vol 35, pg 12595, 2020)

On the Dynamic Performance of Laterally Gated Transistors

Coss Loss Tangent of Field-Effect Transistors: Generalizing High-Frequency Soft-Switching Losses

Impact of Embedded Liquid Cooling on the Electrical Characteristics of GaN-on-Si Power Transistors

Active-Device Losses in Resonant Power Converters: A Case Study with Class-E Inverters

Enhanced-DAB Converter: Comprehensive Design Evaluation

New Insights on Output Capacitance Losses in Wide-Band-Gap Transistors

Comparison of Wide-band-gap Technologies for Soft-Switching Losses at High Frequencies