what is the requirement of the opamp for an opamp buffer?

[ug02048]

ie what is the gain typically ?

input resistance
output resistance etc


many thanks

 

[IanP]

Re: what is the requirement of the opamp for an opamp buffer

Using general terms the gain of a buffer is 1, input impedance is as high as possible and output impedance as low as possible. For example, the input impedance will vary from (10)5 to (10)9 Ω .. for different types of opamps ..

 

[muldersun]

It need to trade off each parameter.You can choose fitable circuit depend on you application requirements.

 

[jiangwp]

Re: what is the requirement of the opamp for an opamp buffer

As a output buffer with opamp, it is closed loop with unity gain.

It is the voltage-voltage feeback type. therefore, this results in the close loop large input impedence and small output impedence. So the configure is fit for inteface as a buffer.

After close loop, the input impedence is

Rin=Rin0*(1+Aβ)

the output impedence is

Rout=Rout0/(1+Aβ)

the BandWith is

UBW=UBW0*(1+Aβ)

So maybe depending on you application, you can select the open gain ,the open loop input impdence ,output impdence and bandwith.

 

[alvays]

the other requirements may be the suitable driving current to drive load, and the swing range, better to be ratio to ratio.

the answer of voltage-voltage feedback given by preceding is excellent. it not only give a non-inverting, but also meet the performance.