28,619 research outputs found
W-band low-noise amplifier with 50 nm In<inf>0.8</inf>GaP/In<inf>0.4</inf>AlAs/In<inf>0.35</inf>GaAs metamorphic HEMT
No full textW-band low-noise amplifier (LNA) has been successfully demonstrated with 50 nm metamorphic HEMT (MHEMT) technologies. 50 nm MHEMT showed a g m.max of 760 mS/mm, a fT of 216 GHz, and a fmax of 400 GHz in spite of indium content of 35 % in the channel. W-band LNA with three-stage showed the small signal gain of 9.4 ± 1.8 dB from 40 GHz to 110 GHz. These results are well suited for high frequency applications.N
High performance of W-band MMICs using 60nm InGaAs HEMT technology
No full textA W-band coplanar wave-guide MMIC (a mixer, an oscillator and an ultra broad-band distributed amplifier) has been successfully developed by 60nm gate length InGaAs HEMT technology. 60nm gate length was defined by Si 3N 4SiO 2 sidewall process. The device exhibits good DC and microwave characteristics of V th = -0.65 V, breakdown voltage = -4.1V, extrinsic G m,max = 1.15S/mm, f T= 250 GHz and f max of 263GHz. A mixer exhibits conversion loss of 7dB with 94GHz LO signal and 90GHz RF signal. An oscillator exhibits output power of -4dB at 96GHz. A broadband distributed amplifier achieves small signal gain of 6.6 dB over 0.4∼110GHz. © 2004 IEEE.N
V-band MMIC oscillator array
No full textA y-band strongly-coupled single-chip MMIC oscillator array is presented. For wide bandwidth and easy biasing to push-pull type oscillators, modified 2-port microstrip parasitic coupled antennas are employed. When measured in a closed oversized waveguide, the MMIC oscillator array with two 2-port antennas and four oscillators radiated an output power of 4.4 dBm with excellent spatial power combining efficiency of 93% at 58.59 GHz.N
W-band divide-by-3 frequency divider using 0.1 mu m InAlAs/InGaAs metamorphic HEMT technology
No full textA W-band divide-by-3 frequency divider with wide bandwidth and low power dissipation is presented using harmonic injection-locking technique. A cascode FET is employed for a self-oscillating second-harmonic mixer which is injection-locked by third-harmonic input to obtain the division order of three. The fabricated frequency divider using 0.1 mu m GaAs metamorphic HEMT technology shows superior performance such as large bandwidth of 6.1 GHz around 83.1 GHz (7.3%) under small DC power consumption of 12 mWN
Genetische Strukturen bei der Koreakiefer (Pinus koraiensis Sieb. et Zucc.) und ihre Veränderung durch Züchtung
No full textDesign guidelines of tunnelling field-effect transistors for the suppression of work-function variation
No full textDesign guidelines to suppress the work-function variation (WFV) effects of tunnelling field-effect transistors (TFETs) have been discussed in comparison with metal-oxide-semiconductor FETs for the first time. The effects of metal-gate materials and their grain size on the WFV have been investigated. The simulation results show that the selection of appropriate gate material and the reduction of metal grain size are the effective solutions to the WFV of TFETs.N
Miller effect suppression of tunnel field-effect transistors (TFETs) using capacitor neutralisation
No full textA novel method of suppressing the Miller effects of tunnel field-effect transistors (TFETs) is proposed by using capacitor neutralisation. Since TFETs suffer from more severe Miller effects than metal-oxide-semiconductor FETs, conventional ways such as short-gate structures are not sufficient to fully suppress the Miller effects of TFETs. For further reduction of Miller effects, capacitor neutralisation is applied to TFET circuit design for the first time. An exemplary circuit has been shown to confirm the effectiveness of capacitor neutralisation such as differential cascade voltage switch logic. The suppression of Miller effects has been discussed in terms of undershoot, switching delay, power consumption and circuit area.N
A generalized method to optimize acoustic intensity field by using source array
No full textAcoustically bright zone is defined as a zone where the listener can acquire better sound quality than others. The acoustically bright zone can be generated by improving a desired acoustic variable on a selected zone, and the `zone control’ can be done by controlling multiple sources. Among many possible definitions on the acoustic variables, acoustic intensity is tried as an objective function to enhance the sound power radiation into the listening area. In previous work, acoustic intensity projected to a direction is considered as object function[J.-W. Choi and Y. –H. Kim, “Acoustic intensity optimization using source array,” in Proc. Inter-noise 2003, N777], so that one can maximize acoustic intensity component propagates to the desired direction. This approach shows that acoustic intensity field can be manipulated into a desired direction using a small number of sources, but it sometimes fails to control the direction of intensity. Extending this work, this paper presents a generalized method that can also manipulate the propagating direction of wave front. By employing normalized transfer functions between the multiple sources and measurement points during the optimization process, the directional characteristics of intensity field can be improved
The flip-chip mounted mmic technology using the modified mcmd substrate for compact and low-cost w-band transceiver
No full textWe present novel mufti-chip module (MCM)-D technology to improve the mechanical and thermal properties of a MCM-D substrate for a motherboard of the flip-chip structure. Advantages of the flip-chip mounted MMIC technology using the modified MCM-D substrate were investigated. Based on this investigation the W-band CPW MMIC amplifier using the 0.1-mu m GaAs pHEMT was successfully mounted on the modified MCNI-9 substrate by means of the flip-chip technology. Moreover, the W-band down-converter module with internal local oscillator (LO) source was realized with this technology.N
Spectral kurtosis of choi-williams distribution and hidden markov model for gearbox fault diagnosis
No full textA combination of spectral kurtosis (SK), based on Choi-Williams distribution (CWD) and hidden Markov models (HMM), accurately identifies initial gearbox failures and diagnoses fault types of gearboxes. First, using the LMD algorithm, five types of gearbox vibration signals are collected and decomposed into several product function (PF) components and the multicomponent signals are decomposed into single-component signals. Then, the kurtosis value of each component is calculated, and the component with the largest kurtosis value is selected for the CWD-SK analysis. According to the calculated CWD-SK value, the characteristics of the initial failure of the gearbox are extracted. This method not only avoids the difficulty of selecting the window function, but also provides original eigenvalues for fault feature classification. In the end, from the CWD-SK characteristic parameters at each characteristic frequency, the characteristic sequence based on CWD-SK is obtained with HMM training and diagnosis. The experimental results show that this method can effectively identify the initial fault characteristics of the gearbox, and also accurately classify the fault characteristics of different degrees
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