Hello everyone
While taking the DFTs of a VCO I noticed I was getting significant magnitude components on the spectrum at frequencies that aren't harmonics of the fundamental. I assumed that it was the effect of the varactors I had used to tune the VCO but then to verify this I made a simple ring oscillator as shown below and took its DFT and I am getting a similar result there as well. The oscillator has a fundamental frequency of 3.8536GHz but I see significant magnitudes at 1.5462GHz and 5.4GHz as well and I am not able to explain this conceptually. I have attached my DFT expression also below. Kindly tell me if there is something wrong with the way I am using DFT or explain to me if this is indeed the right behaviour. Any suggestions and explanations will be appreciated.
DFT expression:
dB20(dft(v("/OUT" ?result "tran") 0.0 4e-05 (256 * 256 * 8) "Rectangular" 1 "default" 1.0))
