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Meaning of PAC (Read 1943 times)
designer_dude
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Meaning of PAC
Aug 02nd, 2016, 10:56am
 
Hi all,

I am running PAC, in the default mode for a Time Variant Periodic system. When I plot the output of PAC for particular nodes, I get a set of function labelled by the pss harmonic (call it n). Those functions are plotted from range$ n*f_{PSS} to n*f_{PSS} + f_{sweep}$ where $ f_{sweep}$ is the sweep range. How are those curves related to the transfer function $H_n(f)$ that completely characterize an LTV periodic system in the derivation attached? If they are not related, what is the mathematical definition of the pac output curves?

Thanks!
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Ken Kundert
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Re: Meaning of PAC
Reply #1 - Aug 2nd, 2016, 4:48pm
 
They are the transfer functions. In other words for the nth sideband, the result computed by PAC is the output voltage at nfPSS + fin where fin is the analysis frequency. If the input source has pacmag=1, then the result is the transfer function from the input source at fin to the output at nfPSS + fin.

-Ken
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designer_dude
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Re: Meaning of PAC
Reply #2 - Aug 2nd, 2016, 4:54pm
 
Thanks Kent for the reply.

Why is then the "support" of the transfer function (also called range) plotted only from n*f_pss and not 0 frequency for the transfer function labelled with n?

When I plot G_n(f), which I define to be the gain from f_pacsource to f_pacsource + n * f_pss, I expect the "support" or the frequency range to be from 1k->10G or whatever I defined in the sweep.  

Like G_5(1kHz) for f_pss = 1MHz would be the gain from 1kHz pac modulation to output of 5.001MHz.  This should be defined for 1kHz -> infty ideally.
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Ken Kundert
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Re: Meaning of PAC
Reply #3 - Aug 2nd, 2016, 6:54pm
 
That is under the control of the freqaxis parameter.

-Ken
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