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Oct. 2007, Nov. 2007,Dec. 2007, 2008


Issue 10, Volume 6, October 2007
ISSN: 1109-2734 E-ISSN: 2224-266X







Title of the Paper:  Energy-Based Closing Control Towards Contact De-bounce


Authors: Chieh-Tsung Chi

Abstract: This paper describes the dynamic analysis of contactor system. An ac contactor is modeled and studied focusing on the problem of energy-dissipated efficiency and contact bounce during closing phase. The performance of contact bounce is characterized in terms of a set of variables, the velocity and position of movable part. Afterwards, three cost functions related to the energy dissipation of device are proposed, energy dissipation of coil resistance, energy dissipation of coil inductance, and the kinetic energy of the movable part. The aim is to understand the influence of the applied coil voltage for different initial voltage phases on the contact bounce. The best closing angle for an ac contactor is determined by comparing the kinetic energy needed for moving the movable part in each closing angle. Since the collision velocity or the moving kinetic energy of contact is decreased significantly, hence the electric life and the mechanical life of contactor can then be prolonged and the operating reliability is improved. The validation of the performance of the measurements was performed by means of simulation and experiment approach. Finally, there are some useful and valuable results are obtained and presented too.

Keywords: Contactor, Energy, Contact bounce, Initial phase angle, Closing phase, Movable part, Kinetic energy.

Title of the Paper: GP-based Design and Optimization of a Floating Voltage Source for Low-Power and Highly Tunable OTA Applications


Authors: Maryam Shojaei Baghini, Rajendra Kanphade, D. G. Wakade Priti Gawande, Manisha Chhangani, Manish Patil

Abstract: Reuse of analog building blocks is a time consuming process as CMOS technology scales down. Therefore automatic sizing while taking care of second order effects is of great importance. In this paper a method for automatic sizing and optimization of a floating voltage source (FVS) used in a CMOS Operational Transconductance Amplifier (OTA) is presented. The optimization determines the optimal component values and transistor dimensions for FVS in order to minimize the dissipated power and output impedance. The presented methodology uses geometric programming (GP) and simulation-based optimization in a timeefficient manner. The CMOS FVS is sized initially using convex optimization. Then the design is further optimized by a simulation-based circuit optimizer to include second order effects. Since the initial design uses GP method a globally optimum solution is obtained. The presented approach uses MATLAB version and Cadence Analog Circuit Optimizer. The results are verified by detailed analog simulation using Cadence Analog Design Environment (ADE from IC 5.0.33) in 0.35um mixed-mode CMOS process.

Keywords: Operational Transconductance Amplifier, Convex Optimization, Geometric Programming,
Simulation-based Optimization.

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