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MOSFET Analysis

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A) In comparing the behaviour of an n-channel MOSFET with a p-channel device having identical geometry and threshold voltage, it is found that the n-channel FET has a greater drain current than that of the p-channel FET. State why this should be so and give one other characteristic in which the two devices would differ.

B) In order to increase the packing density, or the number of devices per unit area, that can be achieved on an integrated circuit, the supply voltage has been reduced. Very large scale integrated circuits (VLSI) now work at a 3.3 V supply or below. Give two reasons why it has been necessary to reduce the supply
voltage in order to achieve a higher packing density on the 'chip'.

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Please find attached with one further reference.

A. , generally produce greater comparable drain currents than similarly specified devices. This is a consequence of the fact that the carriers, which happen to be electrons in devices, have greater surface mobility than the charge carriers, which are holes in devices.

The electron surface mobility and hole surface mobility trends are shown below [1]. In general one can say that the electron surface mobility is twice that for holes for similar dimensioned devices

As drain current is directly proportional to charge carrier surface mobility as shown by equation {1} ...

Solution Summary

The solution provides a MOSFET analysis for the given scenarios.

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NMOS FET and BJT Analysis

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3. Coupling capacitors are often used in the input and output stages of an amplifier. Why? What impact do these components have on the amplifier operation? Why? In a bipolar junction transistor amplifier with a base resistor of about 5 k and a collector resistor of about 500 , roughly estimate these capacitors for an audio amplifier that has a frequency response from 100 Hz to 10 kHz?

4. A standard silicon NPN BJT is to be used as an amplifier. The emitter voltage is biased at 4 volts, the base is biased at 5 volts, and the collector is biased at 10 volts. Will this circuit perform as desired? Why or why not.

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