MOS Transistor Inverter: Static Characteristics IResistively Loaded Common-Source Amplifier:The schematic figure of a common-source amplifier with a resistive load is as shown in figure below. The FET is biased into conduction with a d.c. bias voltage, VGS, and an input signal, Vgs, is superimposed on this bias. The output voltage is examined across the drain-source of transistor.
Figure: Schematic figure of a Resistively Loaded MOSFET Amplifier
The amplifier has then both an input and an output circuit characterization as follows:Input Circuit: Vi = VGS = VGS + Vgs Output Circuit: Vo = VDS = VDD – iD RD
By rearranging the second expression we get: VDS/RD = VDD/RD - iDAnd hence,iD = - (1/RD) VDS + (VDD/RD) It is a straight-line relationship of the form y = mx + C, where m = -1/RD and C = VDD/RD. This straight line states the locus of operating point for the output circuit of amplifier. This is termed to as the “load-line” of amplifier and can be plotted from two points:If iD = 0; 0 = - (1/RD) VDS + (VDD/RD) => VDS = VDD, iD = 0 Point 1 If VDS = 0; iD = (VDD/RD) = ID MAX => VDS = 0, iD = VDD/RD Point 2This relationship can be superimposed on the set of characteristic curves of iD vs. VDS for transistor, as shown in figure below.Operation as an Amplifier:Figure below exhibits the locus of operating point of transistor on the load line whenever a signal is applied to the gate of transistor. Whenever the gate voltage is raised above the bias point the drain current rises in response. This in turn raises the voltage drop across RD and as a result the output voltage drops. Whenever the input gate voltage is lowered from the bias value then the drain current reduces in response, the voltage drop across RD drops and therefore the output voltage rises. This can be seen that the phase of output voltage is opposite to that of input and therefore this is an inverting amplifier. From the values given for signal levels, this can be seen that this phase consist only a small gain of less than 2.
Figure: Operation of MOS Transistor as a Voltage Amplifier
VDD = 10V d.c. Bias Conditions: Input: VGS = 4V; Output: VDS = 5.8V, ID = 37µAa.c. Signal Conditions: Input: Vgs = 2Vptp Output: Vds = 3.5 Vptp, id = 32µA ptpVoltage Gain: Vds/Vgs = 3.5V/2V = 1.75 low gain
Operation as a Switch:Figure below exhibits the operation of resistively loaded MOS transistor as the logic switch. The input voltage applied to gate is either logic LO at 0V or logic HI at VDD. Whenever the input voltage is LO at 0V, then VGS applied to the gate is beneath the threshold voltage of transistor, VT, and the transistor is non-conducting or OFF. In this situation, the drain current is zero and there is no voltage drop across the load resistor, RD, and hence the output voltage is pulled up to the supply rail, VDD, as shown at point A on the characteristic. On other hand, when the input voltage applied is a logic HI value of VDD, then the transistor becomes extremely conducting or ON and the drain current increases to its maximum value, ID MAX. In this condition the output voltage goes to its logic LO level, VOL, as shown at point B on characteristic. This can be seen to some finite voltage above zero that depends on the properties of transistor. With appropriate design, the value of VOL can be maintained less than the threshold voltage, VT, and hence this logic LO level can be accurately interpreted by the following logic gate.
Figure: Operation of MOS Transistor as a Logic Switch
Logic Voltages:Input Voltages: For present, the input logic voltages will be taken as ideal and hence:ViL = 0V and ViH = VDDOutput Voltages: Whenever the input is at LO logic level, the transistor is OFF and the output will be pulled up to supply voltage and hence:
VOH = VDDWhenever the input is at HI logic level, the transistor is operating in non-saturation region with utmost drain current flowing. The equation explaining the current-voltage relationship can be resolved beneath these conditions in order to find out the output logic LO voltage. Whenever operating in the non-saturation region the drain current is explained as:ID = Kn[2(VGS - VT) VDS – V2DS]With conditions ID = ID MAX, Vi = VGS = VDD and VDS = VOLOn substituting it gives:ID MAX = Kn[2(VDD - VT) VOL – V2OL]However from the circuit:ID MAX = (VDD - VOL)/RDThus:(VDD - VOL)/RD = Kn[2(VDD - VT) VOL – V2OL]Then,(VDD - VOL)/(KnRD) = 2(VDD - VT) VOL – V2OLOn re-arranging it gives:VDD/(KnRD) = [(1/ KnRD) + 2(VDD - VT) VOL – V2OLV2OL – [(1/ KnRD) + 2(VDD - VT)]VOL + VDD/(KnRD) = 0
When it is supposed that 2(VDD – VT) >> 1/KnRD then this simplifies as:VOL = (VDD - VT) ± √(VDD – VT)2 – (VDD/KnRD)One solution will encompass a value greater than the supply voltage, VDD, and can be rejected to give the value that lies between 0V and VDD and hence in the illustration given with VDD = 10V, VT = 1V, RD = 100kΩ and Kn = 100µAV-2:
VOL = (10 -1) - √(10 -1)2 – [10/(10-4 105)] = 9 - √81 -1 = 0.05VThis value is acceptable as it is much less than threshold voltage, VT, and therefore can be applied as LO logic level to an identical circuit.
Latest technology based Electrical Engineering Online Tutoring Assistance
Tutors, at the www.tutorsglobe.com, take pledge to provide full satisfaction and assurance in Electrical Engineering help via online tutoring. Students are getting 100% satisfaction by online tutors across the globe. Here you can get homework help for Electrical Engineering, project ideas and tutorials. We provide email based Electrical Engineering help. You can join us to ask queries 24x7 with live, experienced and qualified online tutors specialized in Electrical Engineering. Through Online Tutoring, you would be able to complete your homework or assignments at your home. Tutors at the TutorsGlobe are committed to provide the best quality online tutoring assistance for Electrical Engineering Homework help and assignment help services. They use their experience, as they have solved thousands of the Electrical Engineering assignments, which may help you to solve your complex issues of Electrical Engineering. TutorsGlobe assure for the best quality compliance to your homework. Compromise with quality is not in our dictionary. If we feel that we are not able to provide the homework help as per the deadline or given instruction by the student, we refund the money of the student without any delay.
Simple Harmonic Motion II tutorial all along with the key concepts of Mass Hanging from a Coiled Spring, Period of Oscillation, Simple Pendulum, Energy of Simple Harmonic Motion, Kinetic Energy, Potential Energy
The significant objectives of the uniform costing - To help for meaningful and valid cost comparison between the members, To locate and eliminate inefficiencies in the firm by measuring own efficiency in terms of industry generally and in terms of close rivals in particular.
www.tutorsglobe.com offers alkyl halide general reactivity homework help, alkyl halide general reactivity assignment help, online tutoring assistance, organic chemistry solutions by online qualified tutor's help.
Rotational Spectroscopy tutorial all along with the key concepts of Principle of Rotational Spectroscopy, Understanding the Rotational Spectrum, Classification of Molecules Based on Rotational Behaviour
Alternating Current Theory tutorial all along with the key concepts of Effective Value of an Alternating Current or Voltage, Alternating Current Meters, Thermocouple Meter, Half-wave Rectifier and Full-Wave Rectifier
acid-bases and salts-general properties tutorial all along with the key concepts of general properties of acids, uses of acids, properties of bases, uses of bases, types of salts, characteristics of acids, bases and salts, ionization, deliquescence, hygroscopy, efflorescence
tutorsglobe.com benefits from bio fertilizers assignment help-homework help by online role of bio fertilizers tutors
tutorsglobe.com photorespiration assignment help-homework help by online plant physiology tutors
tutorsglobe.com cobb-douglas utility functions assignment help-homework help by online choice and utility maximization tutors
on/off 2 display, left and right selection key, navi key: 4-way scroll key and middle selection, cell key, keypad, end key, microphone, charger connector, audio connector, speaker, camera
a satellite telephone or also termed as sat phone is a type of mobile which connects to orbiting satellites in place of terrestrial cell sites.
tutorsglobe.com etiology assignment help-homework help by online lyme disease tutors
theory and lecture notes of construction and mechanism of operation all along with the key concepts of construction of bjt, operation of n-p-n bjt, current components, minority carrier profile and notation to an n-p-n bjt. tutorsglobe offers homework help, assignment help and tutor’s assistance on construction and mechanism of operation.
switch on the t.v. and test the screen for clear vision and turn the antenna till clear vision is acquired.
Theory and lecture notes of Numerical Methods for Eigenvalues all along with the key concepts of linear algebra, The Power Method, Symmetric Positive-Definite Matrices, Inverse Power Method. Tutorsglobe offers homework help, assignment help and tutor’s assistance on Numerical Methods for Eigenvalues.
1956439
Questions Asked
3689
Tutors
1467496
Questions Answered
Start Excelling in your courses, Ask an Expert and get answers for your homework and assignments!!