Browsing by Author "Chen, K. -H."

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1 fF ESD protection device for gigahertz high-frequency output ESD protection
(2011-09-01)
Lee, J-H.
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Huang, S-C.
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Wu, Y. -H.
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Chen, K. -H.
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電控工程研究所
A mutual-protection scheme is proposed to achieve an ultra-low capacitance electrostatic discharge (ESD) protection device. The ESD protection device can not only dissipate ESD current, but also can make the vulnerable output transistor have the ESD protection capability. Namely, the output transistor can also protect ICs and help the ESD protection device to share the ESD current. Using this scheme can discharge more ESD current than the summation current of the two individual devices. From the ESD test result, it can achieve the required ESD level by using the ultra-low capacitance ESD protection device (similar to 1.2 fF).
Employing dual-saturable-absorber-based filter for stable and tunable erbium-doped fiber ring laser in single-frequency
(2011-05-01)
Yeh, C. -H.
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Chow, C. -W.
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Chen, K. -H.
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Chen, J. -H.
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光電工程學系
In this demonstration, a stable and wavelength-tunable erbium-doped fiber (EDF) ring laser using dual-saturable-absorber-based (DSAB) filter inside loop cavity is proposed and experimentally investigated. The proposed DSAB filter not only can filter the side-mode in single-frequency output, but also can obtain the flattened output power spectrum within 1 dB variation in the effectively range of 1529 to 1563 nm. In addition, the output stabilities of wavelength and power are also measured experimentally and discussed.
Low-complexity hopping DFT design based on a compact recursive structure
(2017-01-05)
Juang, W. -H.
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Lai, S. -C.
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Chen, K. -H.
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Tsai, W. -K.
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Luo, C. -H.
A novel hopping discrete Fourier transform (DFT) algorithm and its architecture design for efficiently computing time-frequency spectra are presented. Since the sliding process is adopted sample by sample, the spectral bin output data rate is the same as the input data rate. Under the conditions of an M-sample complex input sequence (M = 256), and N-point recursive DFT computation (N = 64) for time hop L (L = 4), the proposed method has the following advantages: (i) the computational complexity of Proposed-I requires only four complex additions and four complex multiplications for each frequency bin, after the first spectral component has been finally calculated; (ii) Proposed-II utilises a re-timing scheme to greatly shorten and balance the critical path; (iii) Proposed-II is less computationally complex than Wang et al.\'s method, as the numbers of multiplication and addition operations in the proposed algorithm are 768 and 1024, representing reductions of 50 and 20%, respectively. In addition, the number of coefficients can be reduced by 50% compared with Park et al.\'s method. In the FPGA implementation, the proposed design can be operated at 47.26 MHz. It is thus more suitable for use with real-time analytic applications of time-frequency spectra.