Operational Amplifier and Application

● Amplifier:-
        

Amplifier is a electronic device , it made of resistance , transistor , diode , capacitor , etc ..

By using Amplifier we can increase power of signal , increase the voltage , current , .

We can classify Amplifiers in two types ..

1. Weak signal Amplifier:-

Weak-signal amplifiers are use primarily in wireless receivers. They are also employed in acoustic pickups, audio tape players, and compact disc players.

2. Strong signal Amplifier :-

Power amplifiers are use in wireless transmitters, broadcast transmitters, and hi-fi audio equipment. The most frequently-used device for power amplification is the bipolor transistor.

●LET US KNOW ABOUT OPERATIONAL AMPLIFIER :-
       

 OP-AMP or  Operational Amplifier is basically building blocks of electronic devices . It's gain very high & operational Amplifier is differential Amplifier with high input impedance and low output impedance . Typical the uses of operational Amplifier are to provide voltage amplitude change . the operational Amplifier contains are oscillator , filter circuit , and many types of circuit . It's usually with external feedback. Used especially in circuit for performing mathematical operational on input voltage. Op-Amp is DC coupled high gain electronic voltage Amplifier with a differential input and usually single ended output . By connecting external component it's gain can controlled. An operational amplifier is an integrated circuit (IC) that operates as a voltage amplifier. An op-amp has a differential input. That is, it has two inputs of opposite polarity. An op-amp has a single output and a very high gain, which means that the output signal is much higher than input signal.
These amplifiers are called "operation" amplifiers because they were initially designed as an effective device for performing arithmetic operations in an analog circuit. The basic circuit of op-Amp is made using a difference amplifier having two inputs & at least one output . As discussed earlier , the + input produces an output that is in phase with the signal applied . Whereas an input to the - ( minus ) input result in an opposite-polarity output .

●Properties of Ideal Op-Amp:-

-high gain
-infinite CMRR
-zero offer voltage
-zero offset current
-zero output impedance
-infinite input impedance
-infinite Bandwidth

●circuit diagram of OP-AMP :-

● Application's of operational Amplifier:-
   

Op-Amp are used in a wide variety of applications in electronics. Some of the more common applications are:

Amplifier can be used in various field , the main application if op Amp below ---

- Voltage follower
 - voltage Adder / voltage summinng
 - voltage subtraction
- integrator
- differentiator
- Analog computer circuit
- function generator circuits
- filter circuits
- output display circuits
- comparator's circuits
- voltage & current regulator circuit
- phase shifting circuits
- signal processing circuit

●Voltage follower:-
     

 Voltage follower is a one of the Application of Op-Amp , op amp which has voltage gain is 1, it means Op-Amp does not provide any amplification to the signal , voltage follower are generally has high input impedance & low output impedance , this means that whatever circuit is supplying the input signal does not have provide much current.
 This high input impedance of voltage follower is the reason of it being used in several circuits. The voltage follower gives an efficient isolation of output from the input signal. The circuit of voltage follower is shown below.

Advantage of Voltage follower op Amp :-

• Provides power gain and current gain.
• Low output impedance to the circuit which uses the output of the voltage follower.
• The Op-amp takes zero current from the input.
• Loading effects can be avoided.

●Voltage summing :- 

         

 We can use Op-Amp as summing of Voltage . Summing amplifier is basically an op amp circuit that can combine numbers of input signal to a single output that is the weighted sum of the applied inputs.

Circuit diagram of Voltage summing in Op-Amp:-

We can express the output voltage in terms of input voltage :- 

We can explain voltage summing through an example ...

Calculate the output voltage of an Op-Amp summing amplifier for the following sets of Voltage & Resistance use   Rf   = 1MEGA OHM in all cases ?
(a). { V1 = +1V , V2 = +2V , V3 = +3V , R1 = 500 Kilo ohm , R2 = 1 mega ohm , R3 = 1 mega ohm } 
(b). { V1 = -2V , V2 = +3V , V3 = +1V , R1 = 200 Kilo ohm , R2 = 500 Kilo  ohm, R3 = 1 mega ohm } 

Advantage of summing Op-Amp :- 

Summing several signals with equal gains is done in an audio mixer. A summing amplifier with different resistors on the inputs gives a weighted sum. This can be used to convert a binary number to avoltage in a digital-to-analog converter.

● Op-Amp as integrator:- 

 Integrator circuit is  most common application of Op-Amp , op-Amp integrator circuit is generally used for perform the the mathematical operation of integration with respect to time; that is, its output voltage is proportional to the input voltage integrated over time. 

Output of square wave in integrator :- 

      

 The square wave is convert in triangular wave form in op Amp integrator circuit . Shown this figure ....

● Advantage of Op-Amp Integrator :- 

  Op-amp Integrator with DC Gain Control , Consequently at low frequencies of the input signal the circuit behaves normally like an integrator. At high frequencies, the capacitor acts as a short circuit and by-passes the resistor R2. The capacitor's reactance in turn reduces the gain of theamplifier.

Operational amplifiers have more important applications and will study them separately.