| Title | A Wideband Voltage Controlled Operational Transconductance Amplifier |
| Author | *Yun-Mi Na, Sung-Ho Yun, Hyeong-Woo Cha (School of Electronic Communication Eng., Cheongju University, Republic of Korea) |
| Page | pp. 545 - 548 |
| Keyword | OTA, current control, high-accuracy, voltage-to current converter |
| Abstract | A wideband voltage controlled operational transconductance amplifier(OTA) for a high-accuracy linear voltage controlled analog systems was designed. The OTA consists of a wideband voltage-to-current converter (VIC) and conventional OTA as shown in Fig.1. The wideband VIC using an adaptive current feedback also was designed. For verification of the performance of the proposed OTA using wideband VIC, we simulated the circuits of the commercial OTA LM13600 and OTA using conventional VIC with the same simulation condition. The simulation result shows that the proposed OTA has a control voltage range with -5.0V to 4.0V (current range with 0μA to 10mA) at supply voltage ±5.0V. The LM13600 and OTA using conventional VIC have the control voltage range with -3.6V to 5.0V and -5.0V to -2.4V, respectively. |
| Title | Conversion of Stability Observed in Van der Pol Oscillator by Unstable Time-Delayed Controller |
| Author | Hiroyuki Shirahama (Ehime University, Japan), Chol-Ung Choe (Darmstadt University of Technology, Germany), *Kazuhiro Fukushima (Kumamoto University, Japan) |
| Page | pp. 549 - 552 |
| Keyword | chaos, synchronization, time-delayed control, trosion free |
| Abstract | We have demonstrated that an unstable time-delayed controller can provide a tool to control the stability of Hopf bifurcation. The unstable time-delayed controller has used to stabilize an unstable periodic orbit operating in subcritical mode. By developing a new coupling method the unstable time-delayed system was improved to be applied for conversion of stability in Hopf bifurcation system. In this study, as an example, conversion of stability of Van der Pol oscillator has been confirmed both experimentally and numerically. The control method would control various oscillations of systems arising from Hopf bifurcation. |
| Title | Image Processing by a Coupled Non-Linear Oscillator System |
| Author | *Naoko Kurata (Chiba University, Japan), Hitoshi Mahara (National Institute of Advanced Industrial Science and Technology, Japan), Tatsunari Sakurai (Chiba University, Japan), Atsushi Nomura, Hidetoshi Miike (Yamaguchi University, Japan) |
| Page | pp. 553 - 556 |
| Keyword | reaction-diffusion system, coupled oscillator, stochastic resonance |
| Abstract | A new algorithm of image processing based on the appropriate solutions of a spatially discrete non-linear oscillator system is presented. This is based on the onset of pattern formation arising in the FitzHugh-Nagumo system with weak-coupled activation and strong-coupled inhibition. The proposed model offers to extract segment or outline of input signals and to be a high performance as noise that is noise reduction and contrast enhancement by noise. Then we discuss the difference between the discrete system of the coupled non-linear oscillators and continuous reaction-diffusion system. |