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Measuring distortion of a bootstrapped switch (Read 3422 times)
Nandish Mehta
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Measuring distortion of a bootstrapped switch
Feb 20th, 2011, 9:48am
 
Hello Friends,

I am designing a low voltage boot strapped switch.

Can any one please suggest me method to measure the distortion of that switch? I am using SPECTRE as circuit simulator.

Any inputs or suggestions will be highly appreciated

Regards
Nandish
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ywguo
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Re: Measuring distortion of a bootstrapped switch
Reply #1 - Mar 2nd, 2011, 6:50am
 
Hi Nandish,

Run transient simulation and do FFT.
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Nandish Mehta
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Re: Measuring distortion of a bootstrapped switch
Reply #2 - Mar 2nd, 2011, 9:11am
 
Hi ywguo,

Sorry for asking such silly question but I am a newbie to design of analog ckts.
I later found out that to measure distortion of boot strap switch I need to do DFT.

However, when I designed the respective test bench I am getting another error. The single tone sinusoid in my test bench is shown as a spread of frequency in my DFT.

My simulations setting information is as below:

1) Input is from ideal sinusiodal voltage source with 3 MHz freq.
2) Sampling frequency for sample and hold is 20 MHz
3) Simulation is ran for 10us
4) 1024 point DFT is calculated with rectangular window

With this issue I cannot rely on the DFT for giving me accurate distortion value. Please suggest me some solution if you know.

Regards
Nandish
Regards
Nandish
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ywguo
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Re: Measuring distortion of a bootstrapped switch
Reply #3 - Mar 7th, 2011, 1:04am
 
Hi Nandish,

Obviously you did not run the bootstrapped switch with coherent sampling. Try to search "coherent sampling" in this forum and google "coherent sampling", you could get a lot of useful message.

Best Regards,
Yawei
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Frank Wiedmann
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Re: Measuring distortion of a bootstrapped switch
Reply #4 - Mar 7th, 2011, 8:19am
 
This is exactly the subject of the link I gave him at http://www.designers-guide.org/Forum/YaBB.pl?num=1298281879/3#3. Seems like he did not understand it...
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