Can Inverters be op-amps?

[patrickian01]

Can inverters, like the ones found on 74LS04 ICs, operate like op-amps? I read somewhere that by connecting the output to the input, it can be made to function like an op-amp. If this is true, then the gain is equal to the feedback resistor value / input resistor value, assuming that that is all there is connected to the inverters, aside from the supplies. Is this all correct? is it really true that inverters can be used as op-amps? what makes inverters different from op-amps?

 

[IanP]

Can inverters, like the ones found on 74LS04 ICs, operate like op-amps? I read somewhere that by connecting the output to the input, it can be made to function like an op-amp. If this is true, then the gain is equal to the feedback resistor value / input resistor value, assuming that that is all there is connected to the inverters, aside from the supplies. Is this all correct? is it really true that inverters can be used as op-amps? what makes inverters different from op-amps?

https://www.electronicspoint.com/ttl-linear-devices-t7353.html

:wink:
IanP

 

[Audioguru]

An opamp has 2 inputs (inverting and non-inverting) but an inverter has only one input so it cannot be an opamp but some inverters can amplify.
I have never seen old TTL inverters used as amplifiers but Cmos inverters like a 74C04 or CD4069 are frequently used as amplifiers.

An opamp usually has very low distortion. A Cmos inverter used as an amplifier has fairly high distortion when the peak-to-peak output voltage approaches the supply voltages.

Here is a graph for Cmos inverters used as amplifiers:

 

[patrickian01]

thank you for your replies.

 

[dick_freebird]

They will amplify, but they will lack many of the canonical
features of the ideal operational amplifier and be inferior
in others.

If you want to use an inverter as a gain stage you may
want to search for the few versions that are actually
single-stage - the multistage ones you will find in a
74xyz04 can be squirrely when you try to hold them
linear or apply slow input edges; the single stage
inverters used to be popular for things like crystal
oscillators.