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Design >> Mixed-Signal Design >> Dac Non Linearity Affecting The baseband noise in SD Mod
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Message started by jefkat on Apr 21^st, 2011, 6:25am

Title: Dac Non Linearity Affecting The baseband noise in SD Mod
Post by jefkat on Apr 21^st, 2011, 6:25am

Hi Guys,
I was simulating a multi-bit sig del Modulator. I notice that when I introduce the non linearity in the DAC (by delibrately adding mismatch in the DAC caps)then besides the appearance of harmonic dist the noise floor of the output of the Modulator, in the baseband, goes up significantly.
What could cause this?. I did the sim in matlab first and then in cadence/spectre. The result is the same in both .
Any interesting ideas?
Thanks for your time.

Title: Re: Dac Non Linearity Affecting The baseband noise in SD Mod
Post by nrk1 on Apr 30^th, 2011, 10:18am

Out of band noise components (which are at a rather high level in a delta sigma modulator) fold into the signal band due to nonlinearity in the DAC and add to the in band noise.

Nagendra