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How to set up DFT in Cadence calculator? (Read 7850 times)
jlee
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How to set up DFT in Cadence calculator?
Feb 20th, 2010, 6:04pm
 
Hi there,

I'm trying to run tran for a frequency divider and use DFT in calculator to get fundamental amplitude, if PSS is not considered to use.

The default setting for DFT is shown below.
Window Type = Rectangular; Smoothing  Factor = 1; Coherent Gain = none
Since the divider output frequency is 2002MHz, I choose the time interval from 200ns to 700ns and the number of samples of 32768(2^15), so that I can get the frequency accuracy of 2MHz.

So, my question is that
for DFT window, there are many types provided in calculator. Which one is more reasonable? An ADC designer suggest me choose the window type as "blackman", but I'm not sura which one is right. Actually, I don't care the output amplitude is 150mV or 151mV. I just wanna know if it is 150mV or 160mV.

I hope you guys can give me some suggestion. Thanks in advance!

Regards

Jason Lee

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pancho_hideboo
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Re: How to set up DFT in Cadence calculator?
Reply #1 - Feb 20th, 2010, 9:44pm
 
jlee wrote on Feb 20th, 2010, 6:04pm:
for DFT window, there are many types provided in calculator. Which one is more reasonable?
An ADC designer suggest me choose the window type as "blackman",
but I'm not sura which one is right.
"Rectangular" window is best for your condition and requirement.
http://en.wikipedia.org/wiki/Window_function

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