Analysis and Modification of an Electro-Oculometer

Abstract

This paper describes an electro-oculometer and analyzes the electronic circuits required to process the signal. This electro-oculometer is a passive, two-channel device which detects the eye orientation using commercially available electrodes attached near the eyes. The electro-oculometer is composed of a special amplifier followed by a parabolic filter. The amplifier has high common mode rejection ratio, low drift, and low input bias current. Both DC and AC analyses of the electro-oculometer have been performed. The common mode rejection ratio (CMRR) of the input stage of the device is computed both at low and high frequencies. The experimental data were then compared with theoretical results. A parabolic low pass filter was designed and implemented as part of the electro-oculometer. A parabolic filter was chosen because it gives a minimum overshoot step response. The input stage (preamplifier) of the electro-oculometer is modified so as to prevent a latch up problem. This latch up is a saturated state of the system. When the output of the system reaches saturation, the system cannot reset itself. The new configuration of the preamplifier does not require any extra active elements

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