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plz post subject name in relation with ur content
anyway GaAs IS HAVING CERTAIN SUPEERMACY OVER SI AND GE IN THE CASE OF MOBILITY. ALSO IT BELONGS TO COMPOUND SEMICONDUCTORS
bouchy,
Self bias refers to any biasing scheme where an external source of bias voltage (or current) is not required.
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In a FET amplifier, this is accomplished by using a resistor between the source and ground (common). Consider an N-channel FET, either JFET or MOSFET. AsS the drain current increases, the voltage across the source resistor increases, thus reducing the Gate-Source voltage, which tends to couneract the effect of the drain current increase. This is negative feedback.
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Consider a bipolar (NPN in my example) amplifier with a collector resistor. Connect another resistor (the bias resistor) between the collector and the base. Now, as th collector current increases, the collector voltage decreases, resulting in a lower voltage across the bias resistor, and, therefore lower base current. The lower base current couneracts the increase in collector current. Again, this is negative feedback.
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Regards,
Kral
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