Question

Find the maximum possible output offset voltage, which is caused by the input offset voltage Vio=15mv?

(a) 0.075v

(b) 0.75v

(c) 0.75v

(d) 7.5v

I had been asked this question in an international level competition.

Query is from Input Offset Voltage in division Operational Amplifier Fundamentals of Linear Integrated Circuits

Answer 1

The correct answer is:

(b) 0.75v

Explanation:

The maximum possible output offset voltage due to the input offset voltage depends on the gain of the amplifier. The formula for the output offset voltage (VooV_{oo}Voo​) caused by the input offset voltage (VioV_{io}Vio​) is:

Voo=Vio×AV_{oo} = V_{io} \times AVoo​=Vio​×A

Where:

• VooV_{oo}Voo​ is the output offset voltage.
• VioV_{io}Vio​ is the input offset voltage.
• $A$ is the gain of the amplifier.

Given:

• Input offset voltage Vio=15 mVV_{io} = 15 \, \text{mV}Vio​=15mV
• Gain $A$ (usually assumed for the op-amp in the absence of any additional information) is typically high, around 50 for many standard op-amps.

If the gain is 50, the output offset voltage is:

Voo=15 mV×50=0.75 VV_{oo} = 15 \, \text{mV} \times 50 = 0.75 \, \text{V}Voo​=15mV×50=0.75V

Thus, the maximum possible output offset voltage is 0.75V.