• Journal of Power Electronics
• /
• 제18권4호
• /
• pp.1255-1267
• /
• 2018

Parasitic parameters have a larger influence on Silicon Carbide (SiC) devices with an increase of the switching frequency. This limits full utilization of the performance advantages of the low switching losses in high frequency applications. By combining a theoretical analysis with a experimental parametric study, a mathematic model considering the parasitic inductance and parasitic capacitance is developed for the basic switching circuit of a SiC MOSFET. The main factors affecting the switching characteristics are explored. Moreover, a fast-switching double pulse test platform is built to measure the individual influences of each parasitic parameters on the switching characteristics. In addition, guidelines are revealed through experimental results. Due to the limits of the practical layout in the high-speed switching circuits of SiC devices, the matching relations are developed and an optimized layout design method for the parasitic inductance is proposed under a constant length of the switching loop. The design criteria are concluded based on the impact of the parasitic parameters. This provides guidelines for layout design considerations of SiC-based high-speed switching circuits.

• 대한전기학회논문지
• /
• 제40권6호
• /
• pp.582-589
• /
• 1991

We used Cd Se as the semiconductor to analyze the Poly-TFT. Cd Se TFT is fabricated by the vacuum evaporation method and the characteristics curves of the current-voltage are obtained using the results of measurement of Cd Se TFT devices. Employing least square method and Rosenbrock algorithm, we can extract the device parameters(grain boundary mobility, trap density). The current-voltage relations calculated by extracted parameters are in good agreement with experimental results.

• 한국항해학회지
• /
• 제16권3호
• /
• pp.65-76
• /
• 1992

An algorithm to determine the optimum nominal value of geometrical and material parameters in divice modelling is proposed. The algorithm uses the yield and variance prediction formula and Monte-Carlo analysis. The performance specification of the noise figure must also be satisfied. In this paper, the total number of considered devices is 1000, and each parameter of geometrical and material parameters is generated randomly within the limits of ${\pm}3%$ of nominal value, and the distribution of 1000 geometrical and material parameters is gaussing distribution.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제17권1호
• /
• pp.185-201
• /
• 2023

Grant-free random access (GFRA) can reduce the access delay and signaling cost, and satisfy the short transmission packet and strict delay constraints requirement in internet of things (IoT). IoT is a major trend in the future, which is characterized by the variety of applications and devices. However, most existing studies on GFRA only consider a single type of device and omit the effect of access delay. In this paper, we study GFRA in multicell massive multipleinput multiple-output (MIMO) systems where different types of devices with various configurations and requirements co-exist. By introducing the backoff mechanism, each device is randomly activated according to the backoff parameter, and active devices randomly select an orthogonal pilot sequence from a predefined pilot pool. An analytical approximation of the average spectral efficiency for each type of device is derived. Based on it, we obtain the optimal backoff parameter for each type of devices under their delay constraints. It is found that the optimal backoff parameters are closely related to the device number and delay constraint. In general, devices that have larger quantity should have more backoff time before they are allowed to access. However, as the delay constraint become stricter, the required backoff time reduces gradually, and the device with larger quantity may have less backoff time than that with smaller quantity when its delay constraint is extremely strict. When the pilot length is short, the effect of delay constraints mentioned above works more obviously.

• 한국전기전자재료학회논문지
• /
• 제11권5호
• /
• pp.347-352
• /
• 1998

In this paper, the extraction and optimization of SPICE parameters on SONOSFET for NVSM circuit design were discussed. SONOSFET devices with different channel widths and lengths were fabricated using conventional 1.2 um n-well CMOS process. And, electric properties for dc parameters and capacitance parameters were measured on wafer. SPICE parameters for the SONOSFET were extracted from the UC Berkeley level 3 model for the MOSFET. And, local optimization of Ids-Vgs curves has carried out in the bias region of subthreshold, linear, saturation respectively. Finally, the extracted SPICE parameters were optimized globally by comparing drain current (Ids), output conductance(gds), transconductance(gm) curves with theoretical curves in whole region of bias conditions. It is shown that the conventional model for the MOSFET can be applied to the SONOSFET modeling except sidewalk effect.

• ETRI Journal
• /
• 제27권3호
• /
• pp.319-325
• /
• 2005

In this paper the effect of temperature on the electrical properties of organic semiconductor disperse orange dye 25 (OD) have been examined. Thin films of OD have been deposited on $In_{2}O_{3}$ substrates using a centrifugal machine. DC current-voltage (I-V) characteristics of the fabricated devices $(Al/OD/In_{2}O_{3)$ have been evaluated at varying temperatures ranging from 40 to $60^{\circ}C$. A rectification behavior in these devices has been observed such that the rectifying ratio increases as a function of temperature. I-V characteristics observed in $Al/OD/In_{2}O_{3)$ devices have been classified as low temperature $({\leq} 50^{\circ}C)$ and high temperature characteristics (approximately $60^{\circ}C$). Low temperature characteristics have been explained on the basis of the charge transport mechanism associated with free carriers available in OD, whereas high temperature characteristics have been explained on the basis of the trapped space-charge-limited current. Different electrical parameters such as traps factor, free carrier density, trapped carrier density, trap density of states, and effective mobility have been determined from the observed temperature dependent I-V characteristics. It has been shown that the traps factor, effective mobility, and free carrier density increase with increasing values of temperature, whilst no significant change has been observed in the trap density of states.

• 한국전산유체공학회지
• /
• 제20권1호
• /
• pp.77-83
• /
• 2015

Flow characteristics of synthetic jet based flow supplying devices have been computationally investigated for different device shapes. Jet momentum was produced by the volume change of a cavity by two piezoelectric-driven diaphragms. The devices have additional flow path compared with the original synthetic jet actuator, and these flow path changes the flow characteristics of synthetic jet actuator. Four non-dimensional parameters, which were functions of the shapes of the additional flow path, were considered as the most critical parameters in jet performance. Comparative studies were conducted to compare volume flow rate and jet velocity. Computed results were solved by 2-D incompressible Navier-Stokes solver with k-w SST turbulence model. Detailed computations revealed that the additional flow path diminishes suction strength of the synthetic jet actuator. In addition, the cross section area of the flow path has more influence over the jet performances than the length of the flow path. Based on the computational results, the synthetic jet based flow supplying devices could be improved by applying suitable shape of the flow path.

• Nuclear Engineering and Technology
• /
• 제48권5호
• /
• pp.1219-1229
• /
• 2016

The present paper reports on a trial to shed further light on the characterization, applications, and operation of radar speed guns or Gunn diodes on different radiation environments of neutron or g fields. To this end, theoretical and experimental investigations of microwave oscillating system for outer-space applications were carried out. Radiation effects on the transient parameters and electrical properties of the proposed devices have been studied in detail with the application of computer programming. Also, the oscillation parameters, power characteristics, and bias current were plotted under the influence of different ${\gamma}$ and neutron irradiation levels. Finally, shelf or oven annealing processes were shown to be satisfactory techniques to recover the initial characteristics of the irradiated devices.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.2287-2290
• /
• 2003

The electrical characteristics of power devices such as BJT (Bipolar Junction Transistor), and MOSFET (Metal Oxide Field Effect Transistor), etc, are altered due to impinging photon radiation and temperature in the nuclear or the space environment. In this paper, BJT and MOSFET are the two devices subjected to ${\gamma}$ radiation. In the case of BJT, the current gain (${\beta}$) and the collector to Emiter breakdown voltage ($V_{CEO}$) are the two main parameters considered. When it was subjected to ${\gamma}$ rays, the ${\beta}$ decreases as the dose level increases, whereas, $V_{CEO}$ gradually increases as the dose level increases. In the case of MOSFET, the threshold voltage is decreasing as the dose level increases. Here it has been observed the decent rate is an increasing function of the threshold voltage. The on-resistance does not change with respect to the dose. Both the devices recover back the original specification after the annealing is finished. No permanent damage has been occurred.

• 산업기술연구
• /
• 제28권B호
• /
• pp.245-250
• /
• 2008

Recently, mobile devices have supported wireless LAN as well as bluetooth, where the services such as heterogeneous network access and seamless mobility connection are important. Even though the mobility and physical network might be varied, an efficient communication mechanism for the network access and a robust mobility management of mobile devices are needed. In this paper, we design and implement a Bluetooth system with mobile LAN access capability. The proposed system has the following features; 1) IP connection is enabled by BENP in the link layer, 2) The networks devices of heterogeneous mobile devices are integrated into a single virtual network interface, 3) IP mobility between the bluetooth and wireless LAN is supported by mobile IP. The experimented results show that the packet loss and delay time during the handover duration is reduced by predicting the handover among different networks followed by the setup of any required parameters in advance.