walker5678
Full Member level 3
what is transfer function
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walker5678 said:I mean if the opamp is not ideal(for most cases, it is the truth), and it's gain is A, output resistance is Ro, what's the transfer function?
Found it's very complicated.
Do you really want to include the output resistor ? Why not also the input impedance ?
walker5678 said:The ideal opamp's output resistance is zero, while actural opamp's ouput resistance is very large, for example, several million ohms, especially for the OTA.
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The "actual opamps output resistance" is rather low.
Neither - nor.walker5678 said:.................
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For the simple two stage amplifier, if the Ids of output stage is 1mA(which is very large for CMOS IC), and lambda is 0.01, then the output resistance is about 0.5/lambda*Ids = 50K.
So is the simple two stage amplifier an operational amplifier or an OTA?
walker5678 said:hehe.... I know your meaning. It's really a difference between naming conventions.
We call the two stage amplifier i mentioned the "non-ideal opamp" , and the opamp you said the "ideal opamp".
Any way, the discussion makes it more clear for the difference between opamps and OTA.