Opamp Low output impedance

SneaKSz

Member

• Feb 1, 2011

• #1

Hello all,

Does someone know a Opamp with a Low output impedance ?

thanks !

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Feb 1, 2011

• #2

They all have low output impedances - it really depends what you mean by 'low', and what you want to do - give more details.

 

SneaKSz

Member

• Feb 1, 2011

• #3

Hello

about a 10 ohm.

Thanks

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Feb 1, 2011

• #4

SneaKSz said:

Hello

about a 10 ohm.

Thanks

Click to expand...

What are you trying to do with it? - and why do you think you need 10 ohm?.

 

SneaKSz

Member

• Feb 1, 2011

• #5

I'm experiencing oscillations , lowering the output impedance could stop these oscillations

Thx

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Feb 1, 2011

• #6

SneaKSz said:

I'm experiencing oscillations , lowering the output impedance could stop these oscillations

Click to expand...

Sorry, but I don't think so - try posting your circuit (and a picture of how you've built it), so we can suggest where you may have gone wrong.

 

audioguru

Well-Known Member

Most Helpful Member

• Feb 1, 2011

• #7

Many opamps have an open-loop (no negative feedback) output resistance of 75 ohms. At low frequencies their voltage gain is about 200,000 so the output impedance at low frequencies with negative feedback is 75/200,000= 0.000375 ohms.
But since the open-loop output resistance is 75 ohms then it limits the current if the load is less than about 2k ohms.