| 1. |
- Hjelm, Mats, et al.
(författare)
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Interband tunneling description of holes in Wurtzite GaN at high electric fields
- 2007
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Ingår i: Journal of Computational Electronics. - : Springer Science and Business Media LLC. - 1569-8025 .- 1572-8137. ; 6:1-3, s. 163-166
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the time evolution of an ensemble of holes in Wurtzite GaN under the effect of a high electric field. The density matrix equation used as a foundation in the study includes band-to-band tunneling, but disregards collisions. In the description of the ensemble dynamics the full band structure is used. The average energy and group velocity for the ensemble is calculated, as well as velocity components corresponding to the non-diagonal elements of the velocity operator (interference). The calculations have been carried out for the electric field strengths 0.4 and 4 MV/cm. A comparison is presented of the results with and without inclusion of band tunneling in the ensemble dynamics. There is also a comparison of the velocity with and without the non-diagonal elements of the velocity operator terms. A conclusion is that Monte Carlo simulations considering band tunneling, but not interference, can give accurate results.
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| 2. |
- Kashif, Ahsan-Ullah, et al.
(författare)
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A TCAD approach for non-linear evaluation of microwave power transistor and its experimental verification by LDMOS
- 2010
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Ingår i: Journal of Computational Electronics. - : SpringerLink. - 1569-8025 .- 1572-8137. ; 9:2, s. 79-86
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Tidskriftsartikel (refereegranskat)abstract
- A simulation technique is developed in TCAD to study the non-linear behavior of RF power transistor. The technique is based on semiconductor transport equations to swot up the overall non-linearity’s occurring in RF power transistor. Computational load-pull simulation technique (CLP) developed in our group, is further extended to study the non-linear effects inside the transistor structure by conventional two-tone RF signals, and initial simulations were done in time domain. The technique is helpful to detect, understand the phenomena and its mechanism which can be resolved and improve the transistor performance. By this technique, the third order intermodulation distortion (IMD3) was observed at different power levels. The technique was successfully implemented on a laterally-diffused field effect transistor (LDMOS). The value of IMD3 obtained is −22 dBc at 1-dB compression point (P 1 dB) while at 10 dB back off the value increases to −36 dBc. Simulation results were experimentally verified by fabricating a power amplifier with the similar LDMOS transistor.
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| 3. |
- Kish, Laszlo Bela, et al.
(författare)
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Response to "Comment on 'Zero and negative energy dissipation at information-theoretic erasure'"
- 2016
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Ingår i: Journal of Computational Electronics. - : Springer Science and Business Media LLC. - 1569-8025 .- 1572-8137. ; 15:1, s. 343-346
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Tidskriftsartikel (refereegranskat)abstract
- We prove that statistical information-theoretic quantities, such as information entropy, cannot generally be interrelated with the lower limit of energy dissipation during information erasure. We also point out that, in deterministic and error-free computers, the information entropy of memories does not change during erasure because its value is always zero. On the other hand, for information-theoretic erasure-i.e., "thermalization"/randomization of the memory-the originally zero information entropy (with deterministic data in the memory) changes after erasure to its maximum value, 1 bit/memory bit, while the energy dissipation is still positive, even at parameters for which the thermodynamic entropy within the memory cell does not change. Information entropy does not convert to thermodynamic entropy and to the related energy dissipation; they are quantities of different physical nature. Possible specific observations (if any) indicating convertibility are at most fortuitous and due to the disregard of additional processes that are present.
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| 4. |
- Kish, Laszlo Bela, et al.
(författare)
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Zero and negative energy dissipation at information-theoretic erasure
- 2016
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Ingår i: Journal of Computational Electronics. - : Springer Science and Business Media LLC. - 1569-8025 .- 1572-8137. ; 15:1, s. 335-339
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Tidskriftsartikel (refereegranskat)abstract
- We introduce information-theoretic erasure based on Shannon's binary channel formula. It is pointed out that this type of erasure is a natural energy-dissipation-free way in which information is lost in double-potential-well memories, and it may be the reason why the brain can forget things effortlessly. We also demonstrate a new non-volatile, charge-based memory scheme wherein the erasure can be associated with even negative energy dissipation; this implies that the memory's environment is cooled during information erasure and contradicts Landauer's principle of erasure dissipation. On the other hand, writing new information into the memory always requires positive energy dissipation in our schemes. Finally, we show a simple system where even a classical erasure process yields negative energy dissipation of arbitrarily large energy.
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| 5. |
- Mateos, J., et al.
(författare)
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Monte Carlo modelling of noise in advanced III–V HEMTs
- 2015
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Ingår i: Journal of Computational Electronics. - : Springer Science and Business Media LLC. - 1572-8137 .- 1569-8025. ; 14:1, s. 72-86
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Tidskriftsartikel (refereegranskat)abstract
- One of the main objectives of modern Microelectronicsis the fabrication of devices with increased cutofffrequency and decreased level of noise. At this moment, thebest devices for high-frequency, low-noise behavior areHighelectron mobility transistors (HEMTs) based on InGaAs andInAs channels. In this work, a complete analysis of ultrashort-gate HEMTs has been carried out by using a semiclassicalMonte Carlo simulator, paying special attention tothe noise performance. The validity of the model has beenchecked through the comparison of the simulated results withstatic, dynamic and noise measurements in real HEMTs. Inorder to reproduce the experimental results, we have includedin the model some important real effects such as degeneracy,surface charges, presence of dielectrics and contact parasitics.The cryogenic performance of the HEMTs has alsobeen analyzed. The influence of the parasitic resistances,width of the devices, value of the δ-doping and recess lengthhas been analyzed when scaling down the gate length of thetransistors to 50nm aiming at achieving higher cutoff frequenciesand better noise performance. The important effectof the impact ionization mechanisms and the consequent kinkeffect on the noise in both InGaAs and InAs based HEMTshave also been studied. Finally the advantages of the use of a double gate topology are quantified.
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| 6. |
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| 7. |
- Saez, Yessica, et al.
(författare)
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Current and voltage based bit errors and their combined mitigation for the Kirchhoff-law-Johnson-noise secure key exchange
- 2014
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Ingår i: Journal of Computational Electronics. - : Springer Science and Business Media LLC. - 1569-8025 .- 1572-8137. ; 13:1, s. 271-277
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Tidskriftsartikel (refereegranskat)abstract
- We classify and analyze bit errors in the current measurement mode of the Kirchhoff-law-Johnson-noise (KLJN) key distribution. The error probability decays exponentially with increasing bit exchange period and fixed bandwidth, which is similar to the error probability decay in the voltage measurement mode. We also analyze the combination of voltage and current modes for error removal. In this combination method, the error probability is still an exponential function that decays with the duration of the bit exchange period, but it has superior fidelity to the former schemes.
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| 8. |
- Safavi, Sohrab, et al.
(författare)
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Feasibility analysis of specialized PEEC solvers in comparison to SPICE-like solvers
- 2012
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Ingår i: Journal of Computational Electronics. - : Springer Science and Business Media LLC. - 1569-8025 .- 1572-8137. ; 11:4, s. 440-452
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Tidskriftsartikel (refereegranskat)abstract
- The Partial Element Equivalent Circuit ({PEEC}) method provides an electric equivalent circuit for a physical geometry. This circuit can be combined with external passive/active lumped elements, enabling the simulation of combined circuit and electromagnetic (EM) structures. The resulted circuit can be solved in dedicated solver, or equivalently can be exported to a SPICE-like solver. In this paper, the inclusion of passive and active lumped circuit elements in {PEEC} method has been studied and a combined solver has been developed. To demonstrate the capability of the solver, three structures are examined. All examples include a transmission line-PEEC model and active components. Results are compared with those from OrCAD, where an analytical model for the transmission line is used. Good agreement between the results shows the feasibility of using {PEEC} to solve this type of mixed problems. Also, comparison has been made in terms of implementation and feasibility for the aim of developing the optimal EM solver with active elements support. It is shown that SPICE is not a suitable choice to solve the PEEC models and, a specialized solver can solve the system in a much faster way. On the other hand, all the definitions and models of circuit devices e.g. transistors, MOSFETs, etc. should be implemented in the specialized solver, which raises a trade-off between the solution time and the implementation time.
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| 9. |
- Sakalas, P., et al.
(författare)
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mm-Wave noise modeling in advanced SiGe and InP HBTs
- 2015
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Ingår i: Journal of Computational Electronics. - : Springer Science and Business Media LLC. - 1572-8137 .- 1569-8025. ; 14:1, s. 62-71
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Tidskriftsartikel (refereegranskat)abstract
- DC, RF and noise characteristics of advanced InP/InGaAs and Si/SiGe heterojunction bipolar transistors (HBTs) were measured and modeled in a broad frequency range. Equations for systematically modeled correlated noise in bipolar transistors and their implementation in the compact models HICUM/L0 and L2 are proposed. The models are verified for advanced SiGe HBTs up to 300 GHz by hydrodynamic device simulation and by results from the Boltzmann transport equation. The verified model was used for analyzing the noise of advanced InP/InGaAs and Si/SiGe HBTs. Compared to Si/SiGe HBTs a higher noise at lower frequencies was observed in InP/InGaAs HBTs due to a higher base recombination current. InP HBTs shows a good noise performance beyond 100 GHz and due to their better product can compete with advanced Si/SiGe HBTs for LNA design at mm-wave frequencies.
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