How to view the output noise curve generated by a certain device or subcircuit in noise simulation？

Dear sullying,

zuiying said:

But I want to know the output noise curve contributed by a certain device(for example the MOS in current mirror) or a certain subcircuit(for example the OTA in schemetic). Is there any way?

When you did your search, did you happen to read this Forum post? There are a number of on-line articles discussing how to generate a noise summary file that will show the contributions of your various sources using Assembler or Explorer or using a the ocnGenNoiseSummary() function.

https://community.cadence.com/cadence_technology_forums/f/custom-ic-design/57408/noise-summary-per-instance/1391144#1391144

Shawn

Since the question was about viewing the noise curve from individual devices, a printed noise summary (as suggested by Shawn) doesn't really answer the question.

For that you can use the results browser (Tools→Results Browser) and then navigate to the noise result database and then navigate to the device in question. You can then plot the total noise from that device, or the individual noise contributors. Note that these are all output-referred (i.e. the amount of noise at the output caused by that noise source), not the noise at the device itself. You can get that too, but you need to check the "Noise separation" checkbox on the choose analysis form (in your screenshot).

If you turn on noise-separation, there's some additional items appearing on the Direct Plot Main Form to help find the biggest noise contributors, then the noise at source, the gain from each noise source and so on - each plotted as curves rather than at a spot frequency or integrated over a band. You can also get this info from the results browser too.

Regards,

Andrew

Wow! It is helpful! By the way, if I want to plot the noise cure contributed by a subckt, for example an OTA. The OTA is I0 in the picture below.

It seems that there is no I0 total noise item in psf. If I want to plot the noise cure of I0 total noise, I need to navigate to each MOS device in I0 and add them together? Is there any easier way to plot noise curve of I0 total noise? Thanks a lot.

Wow! It is helpful! By the way, if I want to plot the noise cure contributed by a subckt, for example an OTA. The OTA is I0 in the picture below.

It seems that there is no I0 total noise item in psf. If I want to plot the noise cure of I0 total noise, I need to navigate to each MOS device in I0 and add them together? Is there any easier way to plot noise curve of I0 total noise? Thanks a lot.

Provided that you're only performing a single simulation (this doesn't work well with sweeps/corners - and given that you're using ADE L, my assumption is that you're doing a single simulation), you should be able to add an output:

ocnGenNoiseSummary(1 ?result "noise")

which will generate another output database called "noisesummary" with the total noise from each top-level instance (at level 1 - that's what the 1 in the arguments stands for).

You could also just type this in the CIW after the simulation has completed.

See How do I Create a Noise Summary Automatically in ADE Explorer/Assembler which shows this being used.

Andrew.