ABOUT unit gain buffer ...

[super]

unit gain buffer

Dear all :
I have question about unit gain buffer.
There are three type op.
1. General 2 to 1 op
2. telescopic op
3. folded cascode op

if I connect these op to unit gain buffer ,
what's the different both of them ?


Thanks ..

 

[chingtang]

I think the key difference is the output voltage swing. For telescopic op amp, if you connect the input and output to implement a unity-gain buffer, the output swing is Vth4-(Vgs4-Vth2) [Razavi page 299]. But if you are using a folded cascode op amp, the output swing is higher than the telescopic op amp. Hope this will help. Sorry I am not famillier with the 2 to 1 op amp.

 

[yeechyan]

Do you mean the 2 to 1 op amp is the differential to single ended configuration?

 

[super]

sorry,,,
the 2 to 1 op amp is the differential to single ended configuration.

How about folded cascode and differential to single(D2S) Opamp ?
because folded cascode only open loop gain and Vomax folded is large than
D2S and Vomin are equal .
I don't know what's different between folded and D2S if connect to
Unit gain buffer?

Thanks .