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191.
This letter proposes an open‐ended waveguide antenna with a single split‐ring resonator. In contrast to the waveguide antennas incorporating multiple rings reported in a previous study, which exhibited narrow bandwidth, the proposed antenna uses only one ring to achieve broader bandwidth while keeping the aperture small. A single ring has a relatively low quality factor compared to multiple rings. The simulated and measured fractional bandwidth was 4.13% and 4.03%, respectively, which is much broader than the fractional bandwidth of about 1% demonstrated in a previous study. This simple technique can be used in many applications that require small apertures including near‐field probes and array elements. 相似文献
192.
A Graph-Based Approach to Power-Constrained SOC Test Scheduling 总被引:2,自引:0,他引:2
The test scheduling problem is one of the major issues in the test integration of system-on-chip (SOC), and a test schedule is usually influenced by the test access mechanism (TAM). In this paper we propose a graph-based approach to power-constrained test scheduling, with TAM assignment and test conflicts also considered. By mapping a test schedule to a subgraph of the test compatibility graph, an interval graph recognition method can be used to determine the order of the core tests. We then present a heuristic algorithm that can effectively assign TAM wires to the cores, given the test order. With the help of the tabu search method and the test compatibility graph, the proposed algorithm allows rapid exploration of the solution space. Experimental results for the ITC02 benchmarks show that short test length is achieved within reasonable computation time. 相似文献
193.
Fully‐depleted silicon‐on‐insulator (FD‐SOI) devices with a 15 nm SOI layer thickness and 60 nm gate lengths for analog applications have been investigated. The Si selective epitaxial growth (SEG) process was well optimized. Both the singleraised (SR) and double‐raised (DR) source/drain (S/D) processes have been studied to reduce parasitic series resistance and improve device performance. For the DR S/D process, the saturation currents of both NMOS and PMOS are improved by 8 and 18%, respectively, compared with the SR S/D process. The self‐heating effect is evaluated for both body contact and body floating SOI devices. The body contact transistor shows a reduced self‐heating ratio, compared with the body floating transistor. The static noise margin of an SOI device with a 1.1 µm2 6T‐SRAM cell is 190 mV, and the ring oscillator speed is improved by 25 % compared with bulk devices. The DR S/D process shows a higher open loop voltage gain than the SR S/D process. A 15 nm ultra‐thin body (UTB) SOI device with a DR S/D process shows the same level of noise characteristics at both the body contact and body floating transistors. Also, we observed that noise characteristics of a 15 nm UTB SOI device are comparable to those of bulk Si devices. 相似文献
194.
195.
Chang C.S. Su Y.K. Chang S.J. Chang P.T. Wu Y.R. Huang K.H. Chen T.P. 《Quantum Electronics, IEEE Journal of》1998,34(1):77-83
A novel chirped multiquantum barrier (CMQB) structure was used for AlGaInP light-emitting devices. We have theoretically studied the blocking efficiency of the CMQB structure and found that the CMQB structure is more effective in blocking the electron wave than the conventional uniform multiquantum barrier (UMQB) structure. AlGaInP light emitting diodes (LEDs) with the CMQB structure and the UMQB structure were both fabricated and compared. It was found that the luminescence intensity of the AlGaInP CMQB LED is larger and the intensity distribution of the AlGaInP CMQB LED is more uniform than the AlGaInP UMQB LED. The intensity-current measurement also shows that the electroluminescence intensity of the AlGaInP CMQB LED starts to saturate at a higher injection current 相似文献
196.
The purpose of this paper is to study the relationship between the oxygen concentration and brightness degradation in ZnS:TbOF green thin-film electroluminescent (EL) devices. The characteristics including crystallinity, optical, and electrical properties were discussed. The brightness-voltage (B-V) measurement results shelved that with higher oxygen-content in ZnS:TbOF phosphor layer, lower brightness was measured. It was consistent with the poor crystallinity, worse photoluminescent intensity, and easier to get moisture in the oxygen-rich (O/Tb>1) phosphor film. Furthermore, deep level transient spectroscopy (DLTS) measurements identified that when the O/Tb ratio was greater than 1, the oxygen-related deep hole traps EH1 and/or EH2 could be detected in the ZnS:TbOF phosphor layer. These E H1 and/or EH2 traps were believed to be the main killers for the brightness of the device since they capture most of the holes from the generated electron-hole pairs. This evidence strongly supports that the modified energy transfer model is more dominant than direct impact excitation during the luminescent process 相似文献
197.
Sarkar T.K. Su C. Adve R. Salazar-Palma M. Garcia-Castillo L. Boix R.R. 《Antennas and Propagation Magazine, IEEE》1998,40(5):49-68
The objective of this paper is to present the subject of wavelets from a filter-theory perspective, which is quite familiar to electrical engineers. Such a presentation provides both physical and mathematical insights into the problem. It is shown that taking the discrete wavelet transform of a function is equivalent to filtering it by a bank of constant-Q filters, the non-overlapping bandwidths of which differ by an octave. The discrete wavelets are presented, and a recipe is provided for generating such entities. One of the goals of this tutorial is to illustrate how the wavelet decomposition is carried out, starting from the fundamentals, and how the scaling functions and wavelets are generated from the filter-theory perspective. Examples (including image compression) are presented to illustrate the class of problems for which the discrete wavelet techniques are ideally suited. It is interesting to note that it is not necessary to generate the wavelets or the scaling functions in order to implement the discrete wavelet transform. Finally, it is shown how wavelet techniques can be used to solve operator/matrix equations. It is shown that the “orthogonal-transform property” of the discrete wavelet techniques does not hold in numerical computations 相似文献
198.
Heung Ro Choo Beom-hoan O Chong Dae Park Hyung Mun Kim Jeong Soo Kim Dae Kon Oh Hong Man Kim Kwang Eui Pyun 《Photonics Technology Letters, IEEE》1998,10(5):645-647
The improvement of the linewidth enhancement factor in complex-coupled laser diode (CC-LD), or loss-coupled, was confirmed by measuring the spontaneous emission spectra below threshold from the sidewall of laser diodes. In addition, the serial resistance of the device was measured. The linewidth enhancement factor is improved by the presence of a light absorbing InGaAs grating for loss coupled distributed-feedback (DFB) laser diode (LD). We report the comparison of the linewidth enhancement factors of Fabry-Perot (FP) LD, conventional DFB-LD, and loss coupled DFB-LDs 相似文献
199.
Min-Cheol Oh Hyung-Jong Lee Myung-Hyun Lee Joo-Heon Ahn Seon Gyu Han 《Photonics Technology Letters, IEEE》1998,10(6):813-815
Thermooptic 2×2 switches based on low-loss fluorinated polymer waveguides have been demonstrated. For the waveguide possessing a low-loss around the 1.55-μm wavelength, crosslinkable fluorinated poly(arylene ethers) (FPAE) is developed as a core material and perfluorocyclobutane (PFCB) is used as a cladding material. To enhance the fabrication tolerance and to achieve a low switching power, asymmetric X-junctions with a Mach-Zehnder interferometer are exploited for the polymeric waveguide switches. An inverted rib waveguide structure is fabricated by filling up the etched groove on a lower cladding with the core polymer. The switch exhibits a crosstalk of less than -20 dB, a switching power of 10 mW, and an insertion loss of 4.5 dB 相似文献
200.
Kyung Su Park Dong Ho Cho 《Electronics letters》1998,34(11):1065-1067
A wireless MAC protocol for the CDMA network is proposed which provides the various bit rates required to support the integrated multimedia services. The proposed method improves the spreading codes utilisation efficiency by sharing limited spreading codes among all mobile terminals 相似文献