Evaluation of Digitial Watermarking on Subjective Speech Quality
Kowalczuk Y.; Holub J.
2021 - English Keywords: Speech quality; Watermarking; Speech processing; Transmissions Available in digital repository of ČVUT. Evaluation of Digitial Watermarking on Subjective Speech Quality

Kowalczuk Y.; Holub J.
České vysoké učení technické v Praze, 2021

Non-self-adjoint relativistic point interactions and their approximations by non-local potentials
Tušek, Matěj; Heriban, Lukáš
2021 - English The research project deals with the Dirac operator with non–local potential given by the projec tion on a fixed scaled function from L 2 (R)∩ L 1 (R) multiplied by complex matrix A. The norm–resolvent limit of this not necessarily self–adjoint operator is discussed in this thesis. Furthermore, the rigorous ex pression for the norm resolvent limit is compared to the formal limit of the Dirac operator with non–local potential. This formal limit corresponds to the norm–resolvent limit. In other words, renormalization of the coupling constant does not occur. This property will lead to generalization of the definition of the Dirac operator with relativistic point interaction. Moreover, the spectrum of this newly defined operator is discussed. Remarkable spectral transitions in special cases will be presented. Finally, this spectral transition will be explained by examining ε–pseudospectrum of the operator. Keywords: bodové interakce; Diracův operátor; lokální potenciály; nelokální potenciály; neomezené operátory; nesamosdružené operátory; Dirac operator; local potentials; non–self adjoint operators; non–local potentials; point inter actions; unbounded operators Available in digital repository of ČVUT. Non-self-adjoint relativistic point interactions and their approximations by non-local potentials

The research project deals with the Dirac operator with non–local potential given by the projec tion on a fixed scaled function from L 2 (R)∩ L 1 (R) multiplied by complex matrix A. The ...

Tušek, Matěj; Heriban, Lukáš
České vysoké učení technické v Praze, 2021

Degradation of 600V GaN HEMTs under Repetitive Short Circuit Conditions
Kozárik, J.; Marek, J.; Minárik, M.; Chvála, A.; Debnár, T.; Donoval, M.; Stuchlíková, Ľ.
2021 - English This paper descirbes impact of repetitive short-circuit stress on commercially available 600V e-mode GaN HEMTs with p-GaN gate. The devices were subjected to up to 105 short circuit stress cycles at 100V and 300V drain voltage. Tests at voltages over 300V resulted in destruction of the devices. Electrical characteristics were measured prior to, and after each sequence of pulses to observe gradual effects of repetitive SC stress. The devices were also analysed by DLTS. A shift in all of the measured characteristics was observed. Amount of the shift does not correlate with the number of SC cycles, which suggests more parameters of the devices are affected. The shifts were also more pronounced at higher drain voltage. The trapping was also analysed using DLTS. Due to high complexity of the spectra, only the traps verified by simulation were investigated. At 100V stress voltage, the shift in DLTS spectra was small, at 200V it was significant. Full analysis of possible origin of the observed deep levels is still ongoing. Available in digital repository of ČVUT. Degradation of 600V GaN HEMTs under Repetitive Short Circuit Conditions

This paper descirbes impact of repetitive short-circuit stress on commercially available 600V e-mode GaN HEMTs with p-GaN gate. The devices were subjected to up to 105 short circuit ...

Kozárik, J.; Marek, J.; Minárik, M.; Chvála, A.; Debnár, T.; Donoval, M.; Stuchlíková, Ľ.
České vysoké učení technické v Praze, 2021

Current Instabilities in Large-Area Silicon Diodes: An Accurate TCAD Approach
Balestra, Luigi; Reggiani, Susanna; Gnudi, Antonio; Gnani, Elena; Vobecký, Jan; Vemulapati, Umamaheswara
2021 - English Fast-recovery diodes can exhibit negative differential resistance during reverse recovery which is associated with the formation of current filaments triggered by the presence of inhomogeneities along the device. Physics concerning the dynamics of current filaments has been widely analyzed in literature through numerical simulations. However, a method to clearly identify the elements that dominate on the current pattern formation is still not available since filaments can appear also in uniform structures. In this work, a novel TCAD approach is provided to suppress the numerical errors due to the discretization of the transport equations which allows us to analyze the effects of the junction depth and the presence of different doping inhomogeneities in the anode doping profile of large-area diodes. Available in digital repository of ČVUT. Current Instabilities in Large-Area Silicon Diodes: An Accurate TCAD Approach

Fast-recovery diodes can exhibit negative differential resistance during reverse recovery which is associated with the formation of current filaments triggered by the presence of ...

Balestra, Luigi; Reggiani, Susanna; Gnudi, Antonio; Gnani, Elena; Vobecký, Jan; Vemulapati, Umamaheswara
České vysoké učení technické v Praze, 2021

DEGRADATION OF POWER SIC MOSFET Under REPETITIVE UIS and SHORT CIRCUIT STRESS
Marek, J.; Kozárik, J.; Chvála, A.; Minárik, M.; Stuchlíková, Ľ.
2021 - English This paper investigates the reliability of commercial planar and trench 1.2-kV 4H-SiC MOFSETs under repetitive unclamped inductive switching (UIS) and short circuit (SC) stresses. The degradation of device characteristics, including the transfer characteristics, drain leakage current Idss, and output characteristics, is observed. Repetitive SC stress was performed for 400 and 600 V bus voltages. Increased buss voltages during stress have higher impact on electrical performance of tested devices. The hot carriers injection and trapping into the gate oxide in the channel region may occur during the aging experiments and are believed to be responsible for the variation of electrical parameters. Available in digital repository of ČVUT. DEGRADATION OF POWER SIC MOSFET Under REPETITIVE UIS and SHORT CIRCUIT STRESS

This paper investigates the reliability of commercial planar and trench 1.2-kV 4H-SiC MOFSETs under repetitive unclamped inductive switching (UIS) and short circuit (SC) stresses. The degradation of ...

Marek, J.; Kozárik, J.; Chvála, A.; Minárik, M.; Stuchlíková, Ľ.
České vysoké učení technické v Praze, 2021

Development of an HBM-ESD tester for power semiconductor devices
Maresca, L.; Auriemma, G.; Boccarossa, M.; Borghese, A.; Riccio, M.; Breglio, G.; Irace, A.
2021 - English Recently, the human body model - electrostatic discharge (HBM-ESD) test capability for power diodes was introduced among the requirements in the field of automotive include for a superior reliability. During the HBM-ESD test, the DUT works in avalanche conditions and it is still not well understood the failure modality occurring in power diodes. The available commercial HBM-ESD testers only give information about the maximum voltage rate, without any specific measurement of electrical waveforms. In this work we present a HBM - ESD tester for the characterization of power semiconductor devices up to 6 kV. In the proposed tester both the voltage and current DUT waveforms are measured, for a further gain of the failure analysis in power diodes. Available in digital repository of ČVUT. Development of an HBM-ESD tester for power semiconductor devices

Recently, the human body model - electrostatic discharge (HBM-ESD) test capability for power diodes was introduced among the requirements in the field of automotive include for a ...

Maresca, L.; Auriemma, G.; Boccarossa, M.; Borghese, A.; Riccio, M.; Breglio, G.; Irace, A.
České vysoké učení technické v Praze, 2021

New method for Si-wafer resistivity determination
Hájek, J.; Papež, V.; Horák, M.
2021 - English Wafer resistivity is one of the most important parameters in production of Power Semiconductor Devices (PSD). This parameter is mainly responsible for achieving required breakdown voltage and other electric parameters. Proposal article describes principles and details of newly designed resonant method and new equipment according patent [1] and compares it with commonly known 4point method. This new method is based on resonant measurement of capacity and following calculation. New method exhibits comparable accuracy with 4point method and brings additional advantages. Available in digital repository of ČVUT. New method for Si-wafer resistivity determination

Wafer resistivity is one of the most important parameters in production of Power Semiconductor Devices (PSD). This parameter is mainly responsible for achieving required ...

Hájek, J.; Papež, V.; Horák, M.
České vysoké učení technické v Praze, 2021

Commercial Sweet Spots for GaN and CMOS Integration by Micro-Transfer-Printing
Lerner, Ralf; Hansen, Nis Hauke
2021 - English Several approaches for close integration of power switches with CMOS logic are subject of technical evaluations and academic discussions. This paper identifies the commercially relevant processing steps of different integration methods (HV and SOI CMOS, monolithic integration in SOI and in GaN, Direct Wafer Bonding, micro-Transfer-Printing of GaN on CMOS and CMOS on GaN) and compares them on simple cost per wafer and cost per chip models. Four examples of real ICs verify the simple costs per chip model. Commercially attractive high voltage to logic partitionings are identified for the different integration approaches. Available in digital repository of ČVUT. Commercial Sweet Spots for GaN and CMOS Integration by Micro-Transfer-Printing

Several approaches for close integration of power switches with CMOS logic are subject of technical evaluations and academic discussions. This paper identifies the commercially relevant ...

Lerner, Ralf; Hansen, Nis Hauke
České vysoké učení technické v Praze, 2021

Structure-Aware Compact Thermal Models of Power LEDs
Kuźniak, K.; Szymańska, K.; Starzak, Ł.; Janicki, M.
2021 - English This paper based on the example of white power LEDs illustrates the methodology for the generation of device compact thermal models, whose element values can be assigned physical meaning. The diode thermal behaviour was studied both with the forced water cooling and with the natural convection air cooling. Moreover, owing to the fact that the investigated devices had an electrically isolated thermal pad, the measurements were carried out with the thermal pad properly soldered and with the pad left unconnected, what facilitated the identification of particular sections in the heat flow path. All the measurements of device heating or cooling curves were taken according to the JEDEC standards. The determination of the optical power allowed the computation of the real heating power, which was used then as the input quantity for thermal computations and analyses presented in this paper. Based on the measurement results, thermal structure functions and time constant spectra were computed using the Network Identification by Deconvolution method. The compact thermal models of the investigated LEDs were derived based on the time constant spectra. Owing to the proposed methodology, it was possible to attribute physical meaning to model element values. The accuracy of generated compact models was validated by comparing the simulated heating curves with the measured ones. Although the compact models for the investigated cases consisted only of four RC stages, they provided excellent simulation accuracy with errors below 4% of the maximum temperature rise value. Available in digital repository of ČVUT. Structure-Aware Compact Thermal Models of Power LEDs

This paper based on the example of white power LEDs illustrates the methodology for the generation of device compact thermal models, whose element values can be assigned physical ...

Kuźniak, K.; Szymańska, K.; Starzak, Ł.; Janicki, M.
České vysoké učení technické v Praze, 2021

TEMPERATURE DISTRIBUTION IN THE COATBACT OF A PARTIALLY FIRE-PROTECTED MEMBER
Dobrovolný P.; Šejna J.; Wald F.
2021 - English Whenever fire unprotected steel members are attached to a fire-protected steel member and penetrate its passive fire protection, additional heat will be conducted to this member during a fire. This can result in a local hot spot in the primary member that may reduce the actual fire resistance. The wide variation in loss of fire resistance is because geometries can vary, and in particular because of the influence of the section factors of the attachments. The influence of the partial protection was experimentally and numerically studied at the Czech Technical University in Prague. Four partially fire-protected plates were heated according to the nominal standard fire curves in a small horizontal furnace. A Finite Element Analysis (FEA) was validated and was applied to a numerical study of an unprotected steel beam under fire separation sealing, which was connected to a steel column. A description was prepared of the development of heat for various fire exposures under fire protection of different lengths and nonlinear thermal conductivity with different section factors. Keywords: steel structures; fire design; fire protection; beam; coatback Available in digital repository of ČVUT. TEMPERATURE DISTRIBUTION IN THE COATBACT OF A PARTIALLY FIRE-PROTECTED MEMBER

Whenever fire unprotected steel members are attached to a fire-protected steel member and penetrate its passive fire protection, additional heat will be conducted to this member during a fire. This ...

Dobrovolný P.; Šejna J.; Wald F.
České vysoké učení technické v Praze, 2021