2006 Fiscal Year Final Research Report Summary
Development of high-speed LiNb3 optical switch with CMOS driver circuit
| Project/Area Number |
15360032
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied optics/Quantum optical engineering
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| Research Institution | KYUSHU UNIVERCITY |
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Principal Investigator |
YOSHIDA Keiji Kyushu University, Faculty of Information Science and Electrical Engineering, Professor, 大学院システム情報科学研究院, 教授 (80108670)
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| Co-Investigator(Kenkyū-buntansha) |
KANAYA Haruichi Kyushu University, Faculty of Information Science and Electrical Engineering, Associate Professor, 大学院システム情報科学研究院, 助教授 (40271077)
POKHAREL Ramesh Kyushu University, Faculty of Information Science and Electrical Engineering, Research Associate, 大学院システム情報科学研究院, 助手 (60403911)
KANDA Yutaka Fukuoka Institute of Technology, Faculty of Engineering, Professor, 工学部, 教授 (10140807)
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| Project Period (FY) |
2003 – 2006
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| Keywords | Optical switch / Transmission line / Microwave device / CMOS driver circuit |
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| Research Abstract |
"Optical switch" is the key device, which changes the route of optical signal without electro-optic conversion. In the high-speed optical communications, external optical switches using a LiNbO_3 and semiconductor devices have already been operated for practical use. There have still been great needs for realizing higher-speed and lower power optical switch for small networks, i.e., router, rather than main networks. The modulation voltage applied from the driver circuit must be transmitted to the open-ended transmission line. In this resarch, we designed the high speed and low-power driver circuit connected to the open-end transmission line for realizing high-speed optical switch.
For realizing the low power dissipation, we adopted the CMOS inverter structure as a core circuit, so that, we obtain the stand-by power less driver circuit. In order to obtain the switching voltage of our LiNbO_3 optical switch, we stacked each nMOS and pMOS FET.
The propagation delay of CMOS inverters depend
… More
s on the load capacitance (C_L) and the output resistance (R_<out>), where C_<out> mainly consists of parasitic capacitance of MOS on this circuit. C_<out> and R_<out> should be small values to suppress the propagation delay. However, when the gate width is increased in order to obtain the small value of R_<out>, C_<out> increases. To solve this problem, we compensated for C_<out> by inserting lumped inductance (L) in the output of the driver circuit. However, in the CMOS process, it is difficult to fabricate large inductance by spiral inductor because of the self-resonance and stray impedances in high frequency range. So, we propose a new method, which decrease C_<out> and gate capacitance by dividing gates width into n stage and compensate each capacitances by inserting transmission lines with high characteristic impedance between the output and input point of the divided drain line and gate line. Switching time from 10% to 90% V_<out> of the distributed type driver is 0.0315 nsec which is 31.5% faster than that of previous version. Less
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