Papers by Keyword: High Frequency

Abstract: We report the development of two epilayers namely the baseline highly strained channel and enhanced low gate leakage samples. The Hall data shows that the enhanced epilayer portraying higher sheet carrier concentration, but comparable carrier mobility in the 2-DEG layer, as compared to the baseline sample. The WinGreen simulation also conformed the enhanced epilayer advantages where wider Schottky barrier is observed and subsequently double carrier concentration is simulated in the channel. Both samples show low AuGe/Au Ohmic contact resistivity of approximately 0.16 Ω.mm. A tremendous advantage on 1 μm Schottky gate leakage is also recorded on enhanced epilayer where the leakage is more than seven times lower than that of the baseline sample. The resulted characteristics are much better than the reported submicron device, thus this device has find an important application in high-gain lossless transmission, especially in underwater optical communication system.

Abstract: This paper presents the realization of CMOS-based current-mode Elliptic ladder band-pass filter by using doubly terminated Elliptic RLC ladder band-pass filter prototype [1], [2]. The proposed circuit contains lossless integrators, lossy integrators and multiple outputs current gains. The frequency response of the proposed circuit can be electronically tuned between 1 MHz and 100 MHz by adjusting bias current between 1μA and 1,000 μA. The proposed circuit uses 1.5 V power supply and 0.1 W power consumption. The passive elements that contained in the proposed filter are only grounded capacitors without using other passive elements that can make this filter suitable for integrated circuit. PSPICE simulation results are carried out by using TSMC 0.18 μm technology and agreed well with the theory.

Abstract: Band saws machine is the most efficient metal cutting machine. By losing less material, material qualitative, having big saw range and having low cutting costs are superiority of band saws. Band saws are acting with most long route and more limited support point in all cutting tools. In band sawing machine, band saws and structure are easy to produce vibration. Affect cutting life, costs of band saws and material surface topography. So this study focuses on analyzing what is vibration cause of band saws by vibration source and establishes the relationship between band saws natural frequency along and change cutting condition. In this research use the C-430GNC band saws machine, and use S45C material for cutting test. Accelerometers are used with a measurement system to capture sawing vibration data. By the fast Fourier transform to analyze spectrogram transform in order to identified characteristic spectrums, and find out vibration feature with band sawing operating conditions and unusual evens came from wear of blade. Minimum cutting vibration and best surface topography were compared to find out the best cutting condition.

Abstract: Ba (Zr_xTi_1-x)O₃ (BZT) films with different Zr contents were deposited on (100)MgO substrates by RF-magnetron reactive sputtering using metal targets. The BZT films epitaxially grew on MgO substrates with only (001)/(100) orientation and had a single perovskite phase. In all cases, the ratio of Ba/Ti was stoichiometry and BZT films possess a dense microstructure. The effect of Zr content on the crystal structure was studied. The grain size was decreased with increasing Zr content. The dielectric properties of the BZT films were also measured at high frequencies region. The reliability of the high-frequency dielectric properties extracted from the measured S₁₁ reflection coefficients. The capacitance for BZT film showed little dispersion and low dielectric loss at 1-18 GHz. These results indicated that we succeeded in depositing high-quality and potential tunable ferroelectrics for high frequency applications.

Abstract: The purpose of the solenoid current control is to decrease holding current of the solenoid by selecting suitable frequency and duty, to keep the solenoid opening reliably for a long time and reduce power consumption and improve the solenoid close feature. In this paper, the high frequency signal in oil pressure holding process is determined by theoretical analysis and experimental study. The purpose of the study is to determine the ideal current in the working process of the solenoid.

Abstract: Due to the ability of the strong anti-interference and directly digital controlling, digital valve has great applications and developing potential in the filed of high frequency response digital servo valve. Base on the rotating structure, a novel high frequency digital valve which can be rotated and controlled in differential parallel way is designed, and the frequency characteristic of electrical signals converting into rotation signals is developed through differential and parallel control of valve spool and valve sleeve. Meanwhile, the hydraulic natural frequency of servo-screw mechanism is further enhanced by the control way of hydraulic half-bridge type A in both chambers of valve spool, and corresponding mathematical model and control block diagram are built. Theoretical analysis concludes that the frequency response characteristic of digital valve is developed significantly. In addition, the multi-gain of rotation angle and axial displacement of valve spool is realized through milling the spiral grooves with different helix angles in the inside of valve sleeve, which improves the flow adaptability of high frequency digital valve effectively. Compared to traditional rotary digital valve, the designed novel digital valve that can be controlled by rotating differentially and parallel has greater advantages in high frequency response and flow adaptability, it provides a new scheme for engineering applications of high frequency digital valve.

Abstract: This article takes non-on-board high frequency charger of pure electric vehicle for research subject, based on the overall structure design, aimed at the deficiency of constant current and constant voltage charging, put forward constant current first, constant voltage afterclose-loop control charging tactics, and analyses charging principle and process in deep, has a certain amount of theoretical research and practical application value.

Abstract: The traditional fatigue machine using stepping motor as driving device has the disadvantages of low efficiency, low frequency and producing heat terribly. This paper presents the development of a new type fatigue machine using voice coil motor which has the advantage of high frequency, high accuracy and easy to control as driving device in order to make up for these deficiencies of the traditional machine. The maximum frequency of fatigue machine can reach 200Hz, and the maximum stroke will reach 30mm. The machine can test the properties of anti-fatigue crack of metal and non-metallic materials and the fatigue lives of mechanical parts. It also can provide the force curve changing with time under different frequencies when carrying on tensile and compressive test on sample, which can greatly improve the accuracy and stability of measuring system

Abstract: This paper was based on the rich theoretical foundation and practical teaching experience, and focused on current teaching situation of high frequency electronic circuit and the cognition of simulation and demo, then it had the positive analysis on the superiority of simulation and demo in high frequency electronic circuit, and it also got the teaching case analysis on simulation and demo of parallel resonant circuit in the high frequency electronic circuit. Through establishment and verification of teaching effect model of high frequency electronic circuit, it can obtain that the teaching presents the advantage of positive feedback through the simulation and demo, and it also can provide new theoretical basis and path of exploration for the teaching research in this field.