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Oct 17th, 2019, 3:51pm
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FFT Plot for Injection Locked PLL output (Read 1180 times)
sarthak
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FFT Plot for Injection Locked PLL output
Apr 28th, 2018, 4:55am
 
Hello,
I am trying to calculate the phase noise of an injection locked PLL by calculating the DFT of the oscillator output waveform. In the DFT plot I see a lot of spurs appearing due to injection locking. But the amplitude level of spurs follows a sinc type distribution. Can someone explain where this sinc response comes from?
Simulation parameters:
Osc. Freq = 2.56GHz
Ref. Freq = 64MHz
Sinc zero crossing = 16.512GHz
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sheldon
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Re: FFT Plot for Injection Locked PLL output
Reply #1 - Apr 28th, 2018, 10:44am
 
Try using either the direct plot of phase noise or he phase noise calculator function.
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sarthak
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Re: FFT Plot for Injection Locked PLL output
Reply #2 - Apr 28th, 2018, 12:37pm
 
I thought that the phase noise function works only on the PSS result data but I am using transient noise simulation. Is there a way to use phase noise function on transient simulation data as well?
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Andrew Beckett
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Re: FFT Plot for Injection Locked PLL output
Reply #3 - Apr 29th, 2018, 12:43am
 
No.
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deba
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Re: FFT Plot for Injection Locked PLL output
Reply #4 - Apr 30th, 2018, 12:47am
 
That Sinc probably appears to be the artifact of windowing the data. Does it change with the window length you have for the FFT?

By the way, if you want phase noise you can directly run the driven PSS/PNOISE simulation to check phase noise.
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