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Design >> Analog Design >> 3rd harmonic distortion cause in sigma delta adc
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Message started by min on May 19^th, 2008, 12:30am

Title: 3rd harmonic distortion cause in sigma delta adc
Post by min on May 19^th, 2008, 12:30am

Hi:

I am simulating a 2nd order sigma delta modulator. it is a cascade switch capacitor structure.

but the slow corner has too high 3rd harmonic = 60dB.

I want to know what cause the 3rd harmonic too high?

thanks

Title: Re: 3rd harmonic distortion cause in sigma delta a
Post by filipe on May 20^th, 2008, 4:33am

Hi,
The first step is verify the specs of your ampop and switch, under corners. The non-linearity of the switches and the non-linearity of the ampop can cause harmonic distortion.
Filipe

Title: Re: 3rd harmonic distortion cause in sigma delta a
Post by chungming on May 22^nd, 2008, 11:36pm

you should check your output of integrator which is saturated.