Opamp input current noise simulation in cadence

[ykxlenny]

Dear all,
I am using cadence to simulate an opamp's input referred current noise. However, i have no idea how to build the test circuit for it; since I cannot use a current source as a input noise source in the noise analysis. If i do, the bias condition will be disturbed. can anyone help me?

Thanks a lot!

 

[erikl]

I suppose you want to simulate this in a true application, meaning the inputs are controlled by a generator with known output impedance? In this case connect the inputs with noiseless resistors to the required bias voltage. Or subtract the resistors noise, if you can't find noiseless resistors in your libs.

 

[crutschow]

Dear all,
I am using cadence to simulate an opamp's input referred current noise. However, i have no idea how to build the test circuit for it; since I cannot use a current source as a input noise source in the noise analysis. If i do, the bias condition will be disturbed. can anyone help me?

You can use a current source. You place the current noise source in parallel with the input with the other end of the noise source to circuit common.
That will properly simulate the resulting input voltage noise due to the circuit input impedance.