differential amplifiers
DESCRIPTION
notes for differential amplifiers(Op-Amps).TRANSCRIPT
LINEAR INTEGRATED CIRCUITS AND
APPLICATIONS [MTE 2104]
1
References:
1. Choudhary Roy D.,Shail B. Jain, “Linear Integrated Circuits”, Wiley Eastern, 2003
2. Stanley William D., “Operational Amplifiers with Linear Integrated Circuits”, Prentice Hall, 2004
3. Franco Sergio, “Design with Op-Amps and Analog Integrated Circuits”, McGraw Hill, 2002
4. Ramakant A. Gayakwad, “Op-Amps and Linear Integrated Circuits”, Prentice Hall India, 2000
5. Robert F. Coughlin and Fredrick F. Driscoll, “Operational Amplifiers and Linear Integrated Circuits”, PHI/Pearson, 2009
2
Introduction to analog system design
• Analog signals are continuous in both time and value.
• Digital signals are discrete in time and value.
3
4
Comparison element Analog signal Digital signal
Analysis Difficult Possible to analyze
Representation Continuous Discontinuous
Accuracy More accurate Less accurate
Storage Infinite memory Easily stored
Subject to Noise Yes No
Recording TechniqueOriginal signal is preserved
Samples of the signal are taken and preserved
Examples Human voice e.t.c Computers e.t.c
Comparison between analog and digital signals:
Analog signal can be depicted using three properties:
Amplitude
Frequency
Phase
5
Integrated circuits(IC’s)
6
IC’s An integrated circuit (IC), sometimes called a
chip is a semiconductor wafer on which
thousands or millions of tiny resistors,
capacitors, and transistors are fabricated.
Two main advantages of IC’s:
– cost and performance.
7
Types of IC’s
• Linear IC: Linear ICs have continuously
variable output that depends on the input signal
level.
• Digital IC: Digital ICs operate at only a few
defined levels or states, rather than over a
continuous range of signal amplitudes.
8
Applications of LICA
• Power amplifiers
• Operational amplifiers
• RF and IF amplifiers
• Voltage comparators
• Multipliers
• Radio receivers
9
Advantages and disadvantages of analog systems
Advantages: Produces a more 'faithful' reproduction of the physical
quantity. make good use of bandwidth- they have power to define
infinite amount of data. No aliasing No quantization noise Analog signal processing can be vastly more simple than a
DSPDisadvantages: Noise and distortion problems Signal cannot be transmitted over long distances. Analog signals require hardware receivers and transmitters
that are designed to perfectly fit the particular transmission. 10
• Resistance:Resistance can be defined as the characteristic of a
medium that opposes flow of current through itself.
Unit:Ω
11
• The current (I) through the resistor (R) is
defined as:
I=V/R
V=I.R
R=V/I
Basics:
12
The power (P) dissipated in (R) is defined as:
P=I.V
P=V2 /R
P=I2 .R• Ex: calculate the value of resistance that will
result in 10 Watts with 10 Volts applied to the circuit shown in below fig.
• Solution: use P=V2 /R or R= V2 /P
Answer:R=10 Ω
13
• Voltage Divider Calculation:Req= R1 + R2
V1 =R1.I and V2 =R2.I
I=Vin/ Req
Vin= V1+ V2
Vin=I.( R1 + R2)
14
To calculate the output voltage :
V2=Vout=I.R2
Vout= R2.Vin / Req
Vout = Vin.R2 /( R1 + R2)
15
Amplifiers• An amplifier or electronic amplifier is an
electronic device that increases the power of
a signal.
16
• Three different kinds of amplifier gains are:
Voltage Gain ( Av )
Current Gain ( Ai )
Power Gain ( Ap )
17
in
outi I
IntInputCurreentOutputCurrAnCurrentGai
ivp xAAAPowerGain
in
outv V
VgeInputVoltaageOutputVoltAnVoltageGai
18
Voltage Gain in dB: av = 20 log Av
Current Gain in dB: ai = 20 log Ai
Power Gain in dB: ap = 10 log Ap