Unit 04 OPERATIONAL AMPLIFIERS Important Q/Ans in Electronic Engineering

Prepare to ace your AKTU Electronic Engineering exams with our complete set of UNIT-4: OPERATIONAL AMPLIFIERS questions and answers. Improve your chances of success by strengthening your grasp of this critical topic.

Dudes 🤔.. You want more useful details regarding this subject. Please keep in mind this as well.

Important Questions For Electronic Engineering:
*Unit-01     *Unit-02    
*Unit-03    *Unit-04 
*Unit-05    *Short-Q/Ans
*Question-Paper with solution 21-22 

Q1. Draw and explain the differential amplifier circuit.    

Ans.

• 1. The emitters are coupled together, and the differential amplifier circuit has two separate inputs and two separate outputs. 
• 2. It also consists of two separate voltage supplies.  

• 3. Due to the common emitter connection in the differential amplifier circuit, the input signal operates both transistors in single-ended mode, producing output from both collectors.
• 4. In a double-ended operation, the difference in the signals applied to the two inputs causes outputs from both collectors when the inputs are different.

• 5. In common-mode operation, a common input signal causes opposite signals to be produced at each collector; these signals cancel one another out and provide a zero as the output signal.
• 6. The primary characteristic of a differential amplifier is its extremely high gain when inputs are provided with opposing signals as opposed to its extremely low gain from common inputs. 
• 7. Let’s consider DC bias operation of the differential amplifier circuit. With each base voltage at 0 V, the common emitter DC bias voltage is  

8. The emitter DC bias current is then, 

• 9. Assuming the transistors are well matched, we get  

Q2. Draw the circuit of an Op-Amp as voltage follower and find an expression for its voltage gain.

Ans. Inverting Op-Amp : 

 1. Fig. shows the basic inverting amplifier with input resistance R₁ and feedback resistance R_f.

Non-inverting amplifier :

1. The circuit for non-inverting amplifier is shown in Fig. 

2. The currents i₁ and i₂ are given as:  

Unity gain Op-Amp (Voltage Follower) : 

Q3. Explain zero crossing detector using OpAmp. 

Ans. When Vr_ef is set to zero, the fundamental comparator can be utilised as a zero crossing detector. A sinusoidal input signal’s output waveform is depicted in Figure together with an inverted zero-crossing detector. The device is additionally known as a sine-to-square wave generator. 

Q4. Determine the output voltage for the given circuit shown in Fig. 

Ans. 

Q5. Determine the output voltage for the given Fig. 

Ans. The output voltage of a summing amplifier is given by 

Q6. Explain the basic parameters of Op-amp. 

Ans. 1. Input bias current: The input bias currents I_B1 and I_B2 are the base bias currents of the two transistors in the input differential amplifier stage of the Op-Amp. An input bias current I_B is defined as the average of the two input bias currents I_B1 and I_B2 that is 

2. Input offset current and voltage :

i. Input offset current : The input offset current, I_iO is defined as the algebraic difference between two input bias currents 1_B1 and 1_B2 

The value of Iw indicates the maximum amount by which the input bias current may differ. 

ii. Input offset voltage : The differential input voltage that exists between two input terminals of an Op-Amp when no external inputs are applied is known as input offset voltage, or V_iO. In order to force the output voltage to zero, it is the amount of input voltage that needs be applied between two input terminals.

3. Slew rate (SR) : It is defined as the maximum rate of change of output voltage per unit of time and is expressed in volts per micro-second i.e.,  

Slew rate describes how quickly an Op-output Amp’s can change in response to an input frequency change.

4. CMRR (common-mode rejection ratio) : It is an ability to reject the common mode noise which is present at both the inverting and non-inverting terminal. 

Electronic Engineering Quantum PDF, Syllabus, Important Questions

Electronic Engineering Quantum PDF | AKTU Quantum PDF:

AKTU Important Links | Btech Syllabus

Important Links-Btech (AKTU)