# Linear Integrated Circuit Questions and Answers – Input Offset Current and Total Output Offset Voltage

This set of Linear Integrated Circuit Multiple Choice Questions & Answers (MCQs) focuses on “Input Offset Current and Total Output Offset Voltage”.

1. The maximum amount by which the two input bias current may differ is known as
a) Input null current
b) Average input bias current
c) Input offset current
d) None of the mentioned

Explanation: The input offset current is defined as the algebraic difference between two input bias current.

2. A 741 type op-amp has a maximum input offset current of 200nA dc. What conclusion can be derived from this statement?
{ IB1 – Input bias current at inverting input terminal and IB2 – Input bias current at non-inverting input terminal}
a) IB1 may be larger than IB2 by 200nA
b) IB2 may be larger than IB1 by 200nA
c) Iio and IB2 may be equal to 200nA
d) All of the mentioned

Explanation: In a 741 op-amp, Iio = 200nA dc, which means that the maximum difference between IB1 and IB2 can be as large as 200nA.

3. The maximum magnitude of the output offset voltage is
a) VOIio = RF*Iio
b) VOIio = RF*( IB1+IB2)
c) VOIio = RF*IB1
d) VOIio = RF*( IB1-IB2)

Explanation: The output offset voltage due to input offset current is given as VOIio = RF*Iio.

4. Find the output offset voltage of an 741 op-amp; If the gain of the non-inverting amplifier is 8.5 and feedback resistor = 15kΩ? (IB=200nA for 741 op-amp)
a) 1µv
b) 4 µv
c) 3 µv
d) 2 µv

Explanation: The circuit diagram of inverting amplifier is given below

Gain, A=1+(RF/R1)
=> R1 = RF/(A-1) = 15kΩ/(8.5-1) = 2kΩ.
=> ROM =(R1* RF)/( R1+RF) = 1.76kΩ.
The output offset voltage, VOIB1= VOIB= RF*IB
=> VOIB1= 1.76kΩ*200nA*8.5 = 2.9×10-6 ≅ 3 µv.

5. Find out the input offset current from the circuit

a) Iio = |IBA*IBC|
b) Iio = |IBA+ IBC|
c) Iio = |IBA/ IBC|
d) Iio = |IBA– IBC|

Explanation: the input offset current is Iio = |IBA– IBC|.
Note: Join free Sanfoundry classes at Telegram or Youtube

6. Determine the maximum output offset voltage caused by input offset current

a) 5.4mv
b) 7.3mv
c) 6.9mv
d) 8.1mv

Explanation: For a 741 op-amp, Iio = 200nA(Maximum).
=> Therefore, VOIio = RF*Iio = 27kΩ*200nA =5.4mv.

7. Find the total output offset voltage of non-inverting op-amp?
a) VooT = {[1+(RF/R1)]*Vio} + RF*Iio
b) VooT = -[(RF/R1)*Vio] + RF*Iio
c) VooT = -[(RF/R1)*Vio] + Iio
d) None of the mentioned

Explanation: The gain of the inverting amplifier A=-(RF/R1). Therefore, the total output offset voltage is given as VooT = -[(RF/R1)*Vio] + RF*Iio.

8. Analyse the circuit and determine the value of total output offset voltage?

The op-amp is the MC1536 with the following specifications:
Vio = 7.5mv, Iio = 5nA, IB =250nA.
a) 0.12v
b) 1.4v
c) 0.76v
d) 8.5v

Explanation: The total output offset voltage due to input offset voltage, VooT = -[(RF/R1)*Vio] + RF*Iio
=> VooT = [1+(47kΩ/470Ω)]*7.5mv+(47kΩ*50nA) = 0.7598 ≅ 0.76v.

Sanfoundry Global Education & Learning Series – Linear Integrated Circuits.