how to clamp the output voltage of opamp

[sumitj]

opamp output voltage clamp

Hi

I have designed an opamp with 5V power supply. when non inverting input is higher than inverting input the output reaches close to positive rail i.e. 5v. I want to design the opmap ( or use some other circuitry) such that the max output voltage doesn't exceed 2.5V. constraints are => power supply can't be changed and also gain of opamp should be greater than 70db.

Thanks

 

[lavitaebelle]

op amp clamp

You need to use negative feedback. With opamp gain>70dB. Even the slightest difference (mV) will send the output to rails due to the high gain. So some form of feedback will get you the desired output level.

 

[lambtron]

Can you simply use a 2:1 voltage divider at the amplifier output?