Browsing by Author "Chen, HC"

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A memory efficient realization of cyclic convolution and its application to discrete cosine transform
(2003)
Chen, HC
;
Guo, JI
;
Jen, CW
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper presents a memory efficient design for realizing the cyclic convolution and its application to the discrete cosine transform (DCT). We adopt the way of distributed arithmetic computation, and exploit the symmetry property of DCT coefficients to merge the elements in the matrix of DCT kernel and then separate the kernel to be two perfect cyclic forms to facilitate an efficient realization of 1-D N-point DCT using (N-1)/2 adders or substractors, one small ROM module, a barrel shifter, and N-1/2 + 1 accumulators. The comparison results with the existing designs show that the proposed design can reduce delay-area product significantly.
A memory-efficient realization of cyclic convolution and its application to discrete cosine transform
(2005-03-01)
Chen, HC
;
Guo, JI
;
Chang, TS
;
Jen, CW
;
電子工程學系及電子研究所
This paper presents a memory-efficient approach to realize the cyclic convolution and its application to the discrete cosine transform (DCT). We adopt the way of distributed arithmetic (DA) computation, exploit the symmetry property of DCT coefficients to merge the elements in the matrix of DCT kernel, separate the kernel to be two perfect cyclic forms, and partition he content of ROM into groups to facilitate an efficient realization of a one-dimensional (1-D) N-point DCT kernel using (N-1)/2 adders or substractors, one small ROM module, a barrel shifter, and ((N - 1)/2) + 1 accumulators. The proposed memory-efficient design technique is characterized by rearranging the content of the ROM using the conventional DA approach into several groups such that all the elements in a group can be accessed simultaneously in accumulating all the DCT outputs for increasing the ROM utilization. Considering an example using 16-bit coefficients, the proposed design can save more than 57% of the delay-area product, as compare with the existing DA-based designs in the case of the 1-D seven-point DCT. Finally, a 1-D DCT chip was implemented to illustrate the efficiency associated with the proposed approach.
Ab initio characterization of electron transfer coupling in photoinduced systems: Generalized Mulliken-Hush with configuration-interaction singles
(2005-12-29)
Chen, HC
;
Hsu, CP
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應用化學系分子科學碩博班
;
Institute of Molecular science
To calculate electronic couplings for photoinduced electron transfer (ET) reactions, we propose and test the use of ab initio quantum chemistry calculation for excited states with the generalized Mulliken-Hush (GMH) method. Configuration-interaction singles (CIS) is proposed to model the locally excited (LE) and charge-transfer (CT) states. When the CT state couples with other high lying LE states, affecting coupling values, the image charge approximation (ICA), as a simple solvent model, can lower the energy of the CT state and decouple the undesired high-lying local excitations. We found that coupling strength is weakly dependent on many details of the solvent model, indicating the validity of the Condon approximation. Therefore, a trustworthy value can be obtained via this CIS-GMH scheme, with ICA used as a tool to improve and monitor the quality of the results. Systems we tested included a series of rigid, sigma-linked donor-bridge-acceptor compounds where "through-bond" coupling has been previously investigated, and a pair of molecules where "through-space" coupling was experimentally demonstrated. The calculated results agree well with experimentally inferred values in the coupling magnitudes (for both systems studied) and in the exponential distance dependence (for the through-bond series). Our results indicate that this new scheme can properly account for ET coupling arising from both through-bond and through-space mechanisms.
All-planar dual-mode asymmetric filters at Ka-band
(2003-03-01)
Chen, HC
;
Tzuang, CKC
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電信工程研究所
;
Institute of Communications Engineering
All-planar dual-mode inductive asymmetric filters utilizing new planar microstrip to dielectric-loaded rectangular waveguide transitions at Ka-band were presented and built in this letter. The conventional, three-dimensional metallic rectangular waveguide dual-mode filters can be implemented into mature PCB technology with a much easier and lower-cost fabrication process on the basis of the all-planar feature of the transition. This work demonstrates two Ka-band filter examples with center frequency at 31 GHz and bandwidth at 1 GHz and 2 GHz. The measured minimum insertion loss of each case was, respectively, 2.68 and 1.12 dB, with greater than 10 dB return loss in the passband. Moreover, the measured side-band attenuation (near passband) is larger than 30 dB due to the transmission zeros at each side of the passband.
Automatic mura detection system for liquid crystal display panels
(2006-01-01)
Fang, LT
;
Chen, HC
;
Yin, IC
;
Wang, SJ
;
Wen, CH
In this paper, we propose an automatic inspection system, which can automatically detect four types of muras on an LCD panel: cluster mura, v-band mura, rubbing mura, and light leakage mura. To detect cluster muras, the Laplacian of Gaussian (LOG) filter is used. A multi-resolution approach is proposed to detect cluster muras of different scales. To speed up the processing speed, this multi-resolution approach is actually implemented in the frequency domain. To detect v-band muras, we check the variation tendency of the projected I-D intensity profile. Then, v-band muras are detected by identifying these portions of the I-D profile where a large deviation occurs. To detect rubbing muras, we designed a frequency mask to detect distinct components in the frequency domain. To detect light leak muras, we apply image mirroring over the boundary parts and adopt the same LOG filter that has been used in detecting cluster muras. All four types of mura detection are integrated together in an efficient way and simulation results demonstrate that this system is indeed very helpful in detecting mura defects.
Automatic mura detection system for liquid crystal display panels - art. no. 60700G
(2006)
Fang, LT
;
Chen, HC
;
Yin, IC
;
Wang, SJ
;
Wen, CH
In this paper, we propose an automatic inspection system, which can automatically detect four types of muras on an LCD panel: cluster mura, v-band mura, rubbing mura, and light leakage mura. To detect cluster muras, the Laplacian of Gaussian (LOG) filter is used. A multi-resolution approach is proposed to detect cluster muras of different scales. To speed up the processing speed, this multi-resolution approach is actually implemented in the frequency domain. To detect v-band muras, we check the variation tendency of the projected I-D intensity profile. Then, v-band muras are detected by identifying these portions of the I-D profile where a large deviation occurs. To detect rubbing muras, we designed a frequency mask to detect distinct components in the frequency domain. To detect light leak muras, we apply image mirroring over the boundary parts and adopt the same LOG filter that has been used in detecting cluster muras. All four types of mura detection are integrated together in an efficient way and simulation results demonstrate that this system is indeed very helpful in detecting mura defects.
Characterization of excimer-laser-annealed polycrystalline silicon films grown by ultrahigh-vacuum chemical vapor deposition
(2000-10-16)
Chen, YC
;
Wu, YCS
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Tung, IC
;
Chao, CW
;
Feng, MS
Polycrystalline silicon (poly-Si) films grown by ultrahigh-vacuum chemical vapor deposition (UHVCVD) system and then annealed by excimer laser at room temperature have been investigated for the applications in polycrystalline silicon thin-film transistors (poly-Si TFTs). The results showed that the grain size of the laser-annealed poly-Si film decreased with laser energy density when a lower laser energy density below 157.7 mJ/cm(2) was used. At about the threshold laser energy density (similar to 134.5 mJ/cm(2)), the finest grain structure could be obtained due to the partial melting in the top layer of the film. When the energy density of the excimer laser was larger than the threshold energy density, the large grain growth was initiated. The largest grain structure could be obtained at similar to 184 mJ/cm(2), while its surface roughness was better than that of the nonannealed UHVCVD poly-Si films. The surface roughening was suggested to arise from the specific melt-regrowth process but not the rapid release of hydrogen or capillary wave mechanism derived from laser-annealed amorphous silicon. By use of the laser-annealed UHVCVD poly-Si films as the active layer, the fabricated poly-Si TFT exhibited a field-effect mobility of 138 cm(2)/V s, a subthreshold swing of 0.8 V/dec, a threshold voltage of 3.5 V, and an on/off current ratio of similar to 10(6). (C) 2000 American Institute of Physics. [S0003- 6951(00)03842-0].
Constrast based color segmentation with adaptive thresholds
(2002)
Chen, HC
;
Chien, WJ
;
Wang, SJ
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, we propose a color segmentation algorithm based on contrast information and adaptive thresholds. Given a color image, instead of the commonly used achromatic difference and chromatic difference, we use achromatic contrast and chromatic contrast to represent the significance of boundary. To fit for human's visual perception, adaptive thresholds are applied to suppress perceptually faint boundaries. A complete segmentation scheme is proposed and the simulation results demonstrate the superiority of this approach in providing reasonable and reliable color segmentation.
Contrast-based color image segmentation
(2004-07-01)
Chen, HC
;
Chien, WJ
;
Wang, SJ
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this letter, we propose a color image segmentation algorithm based on contrast information. Given a color image, we use contrast information, instead of the commonly used derivative information, to detect edges. To fit for human's visual perception, the CIE L*a*b* color space is used and the DeltaE(ab) color difference is adopted as the measure of color contrast. A subjective experiment is made to demonstrate the weak correlation between the perceived color contrast and the levels of (L*, a*, b*). This experiment implies the feasibility of using a single-threshold scheme to suppress perceptually, faint boundaries. A complete segmentation scheme is proposed and the simulation results demonstrate the superiority of this approach in providing reasonable and reliable color image segmentation.
DC to 8 GHz 11 dB gain Gilbert micromixer using GaInP/GaAs HBT technology
(2003-04-17)
Meng, CC
;
Lu, SS
;
Chiang, MH
;
Chen, HC
;
電信工程研究所
A wideband GaInP/GaAs heterojunction bipolar transistor (HBT) micromixer from DC to 8 GHz with I I dB single-ended conversion gain is demonstrated. The input return loss is better than 10 dB for frequencies up to 9 GHz. The single-to-differential input stage in a Gilbert micromixer renders good wideband frequency response and eliminates the need for common-mode rejection. IP1dB = -17 dBm and IIP3 = -7 dBm are achieved for a small local oscillator power of -2 dBm when LO = 5.35 GHz and PF = 5.7 GHz.
Design and investigation of calamitic liquid crystals with low aspect-ratios: rigid y-shaped 1,2,4-tris(4-alkoxyphenylethynyl)benzenes
(2005-12-07)
Hsu, HF
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Chen, HC
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Kuo, CH
;
Wang, BC
;
Chin, HT
The synthesis and characterization of triynylbenzenes, 1-iodo-2,4,5-tri(4-alkoxyphenyl-ethynyl)benzenes (1), are reported, and their structure-mesomorphism relationship is investigated. These compounds possess a y-shaped geometry with rigid linear spacers and a stable nematic phase that was achieved by lengthening the alkoxy chains or replacing the iodo group with a smaller atom. The low aspect ratios and identified calamitic nature of these rigid y-shaped liquid crystals, make them suitable as potential candidates to be used in the liquid crystal layer of liquid crystal display devices for improving viewing angles. In addition, the geometry of I was modified stepwise from a rigid y-geometry to a rigid rectangle for realization of the unstable nematic behaviors of the previously reported board-like 1,2,4,5-tetrakis(4-tridecyloxyphenyl-ethynyl)benzene that was expected to potentially show biaxial nematic phases. The sizes of the fourth side-arm and hence the aspect ratios of these tetra-substituted benzenes are ascribed to the less liquid crystallinity.
Distributed arithmetic realisation of cyclic convolution and its DFT application
(2005-12-01)
Chen, HC
;
Guo, JI
;
Jen, CW
;
Chang, TS
;
電子工程學系及電子研究所
The authors present a new hardware-efficient group distributed arithmetic (GDA) design approach for the one-dimensional (1-D) discrete Fourier transform (DFT). The approach adopts distributed arithmetic (DA) computation and exploits the good features of cyclic convolution to facilitate an efficient realisation of the 1-D N-point DFT using small ROM modules. a barrel shifter, and N accumulators. The proposed GDA design is achieved by rearranging the contents of the ROM into several groups such that all the elements in a group can be accessed simultaneously in accumulating all the DFT outputs to increase ROM utilisation. Moreover, combining the symmetrical property of the DFT coefficients with the proposed GDA design requires only half the ROM contents to be stored, which further reduces ROM size by a factor of two. Realisation of a long-length DFT formulated in cyclic convolution is based on data permutation of the rows and columns in the matrix to directly partition the long-length cyclic convolution into short ones, so that short length DFTs may be realised efficiently by the proposed GDA design to achieve low hardware cost. This design approach is termed the 'block-based group distributed arithmetic approach. Compared with existing systolic array designs and DA-based designs. the proposed GDA design can reduce the delay-area product by 29%-68% based on a 0.35 mu m CMOS cell library.
Downgrading and release rules for control and dummy wafers
(2004-06-01)
Chen, HC
;
Lee, CE
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工業工程與管理學系
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Department of Industrial Engineering and Management
A variety of control and dummy wafers (CD wafers) are utilized in wafer fabrication to enhance product quality and process stability. Wafer fabs downgrade and recycle used CD wafers for cost-down purposes. Downgrading and release rules therefore become crucial issues in CD-wafer management activities but only few studies covered this topic. This study presents a CD-wafer management system, the push system, focusing on downgrading and release rules. The push system attempts to reduce machine delay time, increase recycled usages of CD-wafer lots, and attain a reasonable CD-wafer work-in-process (WIP) level without lowering the throughput rate of product wafers. This study also employs a simulation model of a simplified fab to analyze the performance of the proposed push system. Simulation results demonstrate that the push system leads to efficient utilization of CD wafers. Significance: This work proposes a systematic system, the push system, for downgrading and releases of control and dummy wafers in wafer fabrication. The issue discussed in this study is crucial and practical for wafer fabrication but is seldom cited in research papers.
Effect of carrier gas on the structure and electrical properties of low dielectric constant SiCOH film using trimethylsilane prepared by plasma enhanced chemical vapor deposition
(2004-12-22)
Cheng, YL
;
Wang, Y
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Lan, JK
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Chen, HC
;
Lin, JH
For a low dielectric constant inter-metal dielectric application, the low-k SiCOH film with a dielectric constant of 2.8-3.2 has been deposited by plasma-enhanced chemical vapor deposition (PE-CVD) with trimethylsilane (3MS), oxygen, and the carrier gas. In this work, we present the effects of the carrier gas on the characterizations of the low-k films, including reaction mechanism, the deposition rate, and the mechanical and electrical properties. According to the experimental results, the low-k film in Ar carrier gas exhibits the improvement in deposition rate, nonuniformity, leakage current, and hardness. In addition, the dielectric constant of the deposited low-k film is slightly sacrificed due to the decrease of micropores in the deposited films. (C) 2004 Elsevier B.V. All rights reserved.
LOG filter based inspection of cluster Mura and vertical-band Mura on liquid crystal displays
(2005)
Chen, HC
;
Fang, LT
;
Lee, L
;
Wen, CH
;
Cheng, SY
In this paper, we propose the use of Laplacian of Gaussian (LOG) filters in the detection of Cluster Mura defects and Vertical-Band Mura defects on Liquid Crystal Displays. To detect Cluster Mura defects, 2-D LOG filters with their shapes matching the shapes of Cluster Mura are adopted. The optimal threshold for the detection of Cluster Mura is determined based on the SEMU formula. On the other hand, to detect Vertical-Band Mura, a 1-D LOG filter is used over the projected I-D intensity profile to check if the variation tendency of the intensity profile is changed. The portions with inconsistently intensity variation are regarded as the portions where V-Band Muras occur. The simulation results demonstrate the LOG filters are very useful in the detection of Mura defects.
Multicolor infrared detection realized with two distinct superlattices separated by a blocking barrier
(2002-04-01)
Chen, CC
;
Chen, HC
;
Kuan, CH
;
Lin, SD
;
Lee, CP
A multicolor infrared photodetector was realized with two superlattices separated by a blocking barrier. The photoresponse is switchable between 7.5-12 and 6-8.5 mum by the bias polarity, and is also tunable by the bias magnitude in each wavelength regime. In addition, our detector exhibits advantages including little temperature dependence of the spectral response and the same order of responsivity in the two wavelength regimes. The measured peak responsivities in the two regimes are 117 mA/W at 9.8 mum under 1 V and 129 mA/V at 7.4 mum under -0.8 V, respectively. Also, the detectivities are comparable with the conventional multistack detector. The zero background peak detectivities are 2.3x10(10) cm Hz(0.5)/W at 50 K and 9.8 mum under 0.7 V, and 8.7x10(10) cm Hz(0.5)/W at 70 K and 7.4 mum under -0.7 V. (C) 2002 American Institute of Physics.
Optimization of multiple responses using principal component analysis and technique for order preference by similarity to ideal solution
(2005-12-01)
Tong, LI
;
Wang, CH
;
Chen, HC
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Optimizing multi-response problems has become an increasingly relevant issue when more than one correlated product quality characteristic must be assessed simultaneously in a complicated manufacturing process. This study proposes a novel optimization procedure for multiple responses based on Taguchi's parameter design. The signal-to-noise (SN) ratio is initially used to assess the performance of each response. Principal component analysis (PCA) is then conducted on the SN values to obtain a set of uncorrelated components. The optimization direction for each component is determined based on the corresponding variation mode chart. Finally, the relative closeness to the ideal solution resulting from the technique for order preference by similarity to ideal solution (TOPSIS) is determined as an overall performance index (OPI) for multiple responses. Engineers can easily employ the proposed procedure to obtain the optimal factor/level combination for multiple responses. A case study involving optimization of the chemical-mechanical polishing of copper (Cu-CMP) thin films from an integrated circuit manufacturer in Taiwan is also presented to demonstrate the effectiveness of the proposed procedure.
Performance and application of a superlattice infrared photodetector with a blocking barrier
(2002-02-01)
Chen, CC
;
Chen, HC
;
Hsu, MC
;
Hsieh, WH
;
Kuan, CH
An infrared photodetector that contains a superlattice structure and a blocking barrier was investigated. The photodetector shows advantages including a low operating voltage (<0.7 V), wide detection bandwidth, flexible miniband engineering, and in particular, voltage-tunable spectral responsivity. The blocking barrier not only prohibits the dark current but also acts as a high-pass energy filter to tune the spectral responsivity. The zero background peak detectivity of our detector is 3.7x10(9) cm Hz(0.5)/W (9.7 mum) at -0.5 V and 2.2x10(10) cm Hz(0.5)/W (6.7 mum) at -0.1 V. Since the spectral responsivity at different biases is independent, temperature sensing is feasible by taking the ratio of the measured photocurrent at different biases. A demonstration of temperature sensing by using our superlattice infrared photodetector with a blocking barrier is also shown in this article. Those results show the superlattice is a simple and efficient structure for the design of a multicolor infrared photodetector. (C) 2002 American Institute of Physics.
Pull system for control and dummy wafers
(2003-12-01)
Chen, HC
;
Lee, CEC
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工業工程與管理學系
;
Department of Industrial Engineering and Management
Various CD wafers (Control and Dummy wafers) are used in wafer fabrication to enhance product quality and process stability. Most wafer fabs downgrade used CD wafers into other functional ones and then recycle them to reduce costs. Wafer costs increase with wafer diameter, and thus the downgrading mechanisms and inventory control of CD wafers have become increasingly important to fab performance. Wafer fabs now are willing to seriously consider CD wafer management but CD wafer management remains neglected in the literature. This study presents a novel pull system focusing on inventory and downgrading management of CD wafers. The proposed system in this study intends to reduce the WIP level of CD wafers, increase recycled usages (number of times CD-wafer lots are recycled) before scraping, and reduce machine delay ratio without lowering the product wafer throughput rate.
Relaxation mechanisms of the photoelectrons in the second miniband of a superlattice structure
(2003-02-01)
Chen, CC
;
Chen, HC
;
Hsu, MC
;
Hsieh, WH
;
Kuan, CH
Photoelectron relaxation in the second miniband of a superlattice was studied with a high-pass energy filter at one end of the superlattice. By analyzing the spectral responses with different biases across the energy filter, the photoelectron distribution and relaxation in the second miniband of the superlattice can be resolved. In this paper, a model based on the rate equation is proposed to extract the related parameters of the photoelectron transport. The photoelectrons suffer from both intraminiband and interminiband relaxation. The extracted interminiband relaxation time is 11 ps, while the intraminiband one is in the sulipicosecond range. In addition, this structure can also be utilized as an infrared photodetector. Our analysis shows that the fast intraminiband relaxation is the dominant mechanism of the maximum achievable responsivity of the detector and the theoretical model not only provides the insight of the photoelectron transport in the superlattice miniband but also is useful for designing a superlattice infrared photodetector.