Question

Determine the maximum input signal to be applied to an op-amp to get distortion free output. If the op-amp used is an inverting amplifier with a gain of 50 and maximum output amplitude obtained is 4.2V sine wave?

(a) 159mv

(b) 0.168mv

(c) 207mv

(d) 111mv

I have been asked this question in homework.

My question comes from Slew Rate in chapter Practical Limitations of Op Amp Circuits of Linear Integrated Circuits

Answer 1

To determine the maximum input signal to avoid distortion in the output of an inverting amplifier, we need to consider the gain of the amplifier and the maximum output amplitude.

Given:

• The gain of the amplifier $A=50$
• Maximum output amplitude Vout=4.2VV_{out} = 4.2VVout​=4.2V

The maximum input signal Vin(max)V_{in(max)}Vin(max)​ can be determined using the following relationship for an inverting amplifier:

Vout=−A×VinV_{out} = - A \times V_{in}Vout​=−A×Vin​

Solving for VinV_{in}Vin​:

Vin(max)=VoutAV_{in(max)} = \frac{V_{out}}{A}Vin(max)​=AVout​​

Substituting the values:

Vin(max)=4.2V50=0.084V=84mVV_{in(max)} = \frac{4.2V}{50} = 0.084V = 84mVVin(max)​=504.2V​=0.084V=84mV

However, this value is close to the options provided, so it seems there may be a misunderstanding. The provided options do not match exactly, but the closest correct answer is:

None of the listed options are an exact match, but based on the calculation, 84mV would be the correct value. Please check the problem again for any further constraints or rounding assumptions.