NF plot

[Bogdan, Mocanu]

Hi there, guys.
What is the easiest way to plot the Noise Figure of my single
ended operational amplifier using Spectre from IC5141 ?

- SQD -

 

[Andrew Beckett]

Bogdan, Mocanu wrote, on 07/13/09 11:17:

Hi there, guys.
What is the easiest way to plot the Noise Figure of my single
ended operational amplifier using Spectre from IC5141 ?

- SQD -

Add a "port" from analogLib as the input to your schematic. This is your noisy
input source - generally wants to be impedance matched to the input of your
amplifier (rather like you would on the bench).

You may also want to have a "port" on the output to act as the load.

Then you can either do sp analysis (s-parameter) and specify the "do noise" on
the form, and tell it where the input and output ports are. Or you can use the
"noise" analysis, and specify the input as a port, and output as a probe - and
point to the load port.

Alternatively with noise analysis, you can specify the output as "voltage" and
specify the output nodes. Be aware that in this case it will not subtract the
noise of the load, because it doesn't know what the load is (normally noise
figure is measured excluding the noise in the load, because that's part of your
measurement equipment).

Once the simulation is run, you can use Results->Direct Plot->Main Form and pick
Noise Figure from the sp or noise results.

Regards,

Andrew.