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The resolution of sin wave

Medya

 Hi

I do fft(using dft with N=1024 and set the input freq=100M*17/1024 ,strobperiode=10ns and simulation time>10240ns) on the output of the sin wave,and see that the noise floor is about -100db i repeat it for variuos step(strobperiode) and simtime but the noise floor doesn't vary more,I'm so confused that how can test the high resulotion adc with this low resolution wave,is the way to solve this problem

thanks

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  • Medya

    Thank you alot Andrew,

    finally i have to run the fft analysis(.csv from tran output) with matlab code that i tested it before,(I use the table option in graph window for extracting .csv), but when  the .csv data is used for calculating  sfdr and sndr I noticed that the noise floor was very large,so I used the dft function for comparing and know what was the exact noise floor for ideal sin in this circuit but the results wondered me.then use simple circuit(that you used),in this case the result dont like to yours,too.Now, I dont know waht is the problem ,Is it from simulator or from mistake in doing fft with wrong number of samples?what is your idea?

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  • Medya

    Thank you alot Andrew,

    finally i have to run the fft analysis(.csv from tran output) with matlab code that i tested it before,(I use the table option in graph window for extracting .csv), but when  the .csv data is used for calculating  sfdr and sndr I noticed that the noise floor was very large,so I used the dft function for comparing and know what was the exact noise floor for ideal sin in this circuit but the results wondered me.then use simple circuit(that you used),in this case the result dont like to yours,too.Now, I dont know waht is the problem ,Is it from simulator or from mistake in doing fft with wrong number of samples?what is your idea?

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