You can use F = fft(y) command for Fourier transform in ADS. Where, y is your time domain signal. and then plot 'F' to see the spectrum of the time domain signal.

Dear Dr. Amirreza,

First, you must perform the results in time domain using transient simulation in ADS. Secondly, write an equation as the following format,

(Transient Simulation Name) =fs([Node Name in Schematic],,,,,0,2000us).

Finally, plot the graph using the equation option.

Hi Ahmed S. I. Amar and Vijender Kumar Sharma :

Let's say that I have a circuit like below, how can I perform FFT in ADS?

I'm not sure that the ADS recognizes the FFT function for writing the equation. Can you implement your suggested way on a simple time domain source like the one I attached.

Thanks

first define the output in terms of a equation. For example: y = fft(e) or y = fs(e). Then in the plot options, go to the equation tab and plot y. You will get your FFT.

For more details please see this link:

http://edadocs.software.keysight.com/pages/viewpage.action?pageId=5691317#fs()-1106397

I think the attached files explained the way to see the frequency domain results using the equation option.