Construction and operation of enhancement mosfet, Electrical Engineering

Assignment Help:

Q. Explain the construction and operation of Enhancement MOSFET?

The construction of an N-channel enhancement MOSFET is shown in figure below. Two highly doped N+ regions are diffused in a lightly doped substrate of P-type silicon substrate.

One N+ region is called the source S and other one is called the drain D. They are separated by 1 mil(10-3 inch).A thin insulating layer of SiO2 is grown over the surface of the structure and holes are cut into the oxide layer ,allowing contact with source and drain. Then a thin layer of metal aluminum is formed over the layer of SiO2.This metal layer covers the entire channel region and it forms the gate G.

The metal area of the gate , in conjunction with the insulating oxide layer of SiO2 and the semiconductor channel forms a parallel plate capacitor. This device is called the insulated gate FET because of the insulating layer of SiO2.This layer gives extremely high input impedance for the MOSFET.

If the substrate is grounded and a positive voltage is applied at the gate, the positive charge on G induces an equal negative charge on the substrate side between the source and drain regions. Thus, an electric field is produced between the source and drain regions. The direction of the electric field is perpendicular to the plates of the capacitor through the oxide. The negative charge of electrons which are minority carriers in the P-type substrate forms an inversion layer. As the positive voltage on the gate increases, the induced negative charge in the semiconductor increases. Hence the conductivity increases and current flows from source to drain through the induced channel. Thus the drain current is enhanced by the positive gate voltage.


Related Discussions:- Construction and operation of enhancement mosfet

calculate the current, Find the Thévenin equivalent for the attache...

Find the Thévenin equivalent for the attached circuit and use this to calculate the current in the load.   Circuit information:- Load consists

Explain amplitude-shift keying, Q. Explain Amplitude-shift keying? A ca...

Q. Explain Amplitude-shift keying? A carrier's amplitude is keyed between two levels (binary 1 and 0) in binary ASK. Figure shows the functions of a coherent ASK communication

The input output system - stepper motor , The Input Output System The ...

The Input Output System The input output  system provides  the physical  connection between  the equipment  and the PLC there are many  different kinds  of I/O cards  which ser

Define the signals in time domain, Define the Signals in Time Domain? T...

Define the Signals in Time Domain? The time domain is the type of visualization that most people are familiar with. This method shows variations of a signal with time. The most

Comparison of analog-modulation systems, Comparison of Analog-Modulation Sy...

Comparison of Analog-Modulation Systems The comparison of analog modulation systems (conventional AM, DSB SC, SSB SC, VSB, FM, and PM) can be based on three practical criteria:

engine-based combined heat and power, In this assignment, you will investi...

In this assignment, you will investigate the low-carbon technology that would be most suitable to provide heat and power for a domestic building. • Using information try to iden

Transfer characteristics , Transfer Characteristics The  transfer char...

Transfer Characteristics The  transfer characteristics of power MOSFET   transfer characteristic shown the variation of ID with V GS    denote the drain current  with shorted

What are loosely coupled systems, What are loosely coupled systems? In ...

What are loosely coupled systems? In loosely coupled systems every CPU may have its own bus control logic. The bus arbitration is handled by an external circuit, common to all

Determine and sketch il for inductance, Q. For the circuit of Figure, deter...

Q. For the circuit of Figure, determine and sketch i L (t) and vC(t) for inductance values of (a)3/4 H, (b) 2/3 H, and (c) 3/17 H. Note that the inductance values are chosen her

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd