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Abstract
A great number of people have great difficulty in understanding speech in surrounding with background noise. It is estimated that in the industrialized countries about 10% suffer from heating impairments.
In the past, various devices have been invented to assist those people, Until 1900, they were shaped as tapered horn, But the first commercially available electrical hearing aid device were introduce initially, they only consists of a microphone, a telephone and bulky battery.
But the majok turning point aime when the transistor was invented, since then the hearing aid devices become smaller, and now it is possible to implement the whole system on one or two chips using the VLSI technology. Generally the Hearing Aid systems consists of three main units.
1- The preamprefire.
2- The AGC.
3-The filter.
As the technology advances, the size of the circuit decrease which allow us to decrease the supply voltage, which help us in:
1- Minimize the battery size and hence minimizing the whole system.
2-reduce the power consumption.
In this work our objective is to design a filter for use in hearing aids devices that can work in low voltage, ultra low power environment.
We will use a current mode approach to overcome the problem caused by the reduction in the voltage swing as we decrease the supply voltage.