Hello,

This is my first post here.
I have to design an amplifier using just 741 op-amp(s) and resistors, with the following requirements:
- closed-loop gain: 40dB
- "3dB-frequency" (break frequency): 25kHz
- input impedance: 47kOhm

I'm looking at Microelectronics Circuits (Sedra) and trying to resolve this by using an inverting circuit (one op-amp and 2 resistors) but it doest seem to be a good choice. I can't acomplish all the requirements.

Another question: how can I know the break frequency and open loop voltage gain of 741? (datasheet only mentions 1Mhz of unity-gain bandwidth)

Any advices?

Thanks in advance!

 

Look at the datasheet for a lousy old 741 opamp.
Its output can go up to only 9kHz at 28V peak-to-peak.
Its "break frequency" is only about 6kHz when its gain is 40db.

Use a transistor at its input or another opamp to share the gain.
Use a non-inverting circuit for the fairly high 47k input impedance.