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PAC PXF results (Read 3089 times)

ohms377

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PAC PXF results
Jun 07^th, 2012, 11:20am

Why do PAC vs PXF analysis results differ?

From the sc-filters sample and hold circuit,
I wanted to understand the difference in results
from a PAC and PXF analysis:

clockAlone pss period=TCLK maxacfreq=125/TCLK
directGain pac start=0_Hz stop=10/TCLK maxsideband=25
convGain (sout 0) pxf start=0_Hz stop=10/TCLK maxsideband=25

Note I modified the pxf to have the same start and stop frequency as in the pac analysis.

I have attached an image showing the results.

2012-06-07-112131_984x716_scrot.png

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Re: PAC PXF results
Reply #1 - Jun 7^th, 2012, 8:08pm

PAC gives the transfer function from a particular range of frequencies at the input to a particular sideband of the output. So for sideband #23, the input is at 0_Hz and the output is at 23/TCLK+0_Hz.

PXF gives the transfer function from a particular sideband of the input to a particular range of frequencies at the output. So for sideband #23, the input is at 23/TCLK+0_Hz and the output is at 0Hz.

-Ken

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