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Design >> Mixed-Signal Design >> question about dsm simulation
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Message started by min on Aug 2^nd, 2007, 2:40am

Title: question about dsm simulation
Post by min on Aug 2^nd, 2007, 2:40am

Hi :

I have simulated a third order one bit delta sigma modulator , the input signal is 20KHz,but after simulation i found the fft result contain a dc component. I don't know what cause this dc component.

and I think delta sigma modulator do good to the SNR, but due to nonlinear (like switch capacitor circuit nonideal )cause THD worst. Is that right?

and I also want to know doing a 16 bit delta sigma modulator, usually how much THD equal ?

Thanks!

Title: Re: question about dsm simulation
Post by fran2k5 on Aug 3^rd, 2007, 2:39am

Hi,

if the bit stream at the output goes from 0 to Vdd you will have a dc component due to the fact that the average power is not 0.

About the THD I think that there is not a general rule. It depends on how good is your design.

Regards,

fran2k5