Delta sigma : need help to design

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glias

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Hi all,
I would want to design a DAC that use a delta sigma modulator. Is it possible to design it with a simple microcontroler ? I found this link that present the diagram block of the modulator http://designtools.analog.com/dt/sdtutorial/sdtutorial.html. Is it possible to adapt it with a microcontroler ? the example is a digital output, does a simple analog filter is sufficient to obtain an analog output ?
what is the main advantages of this method comparating to the PWM + analog filter to obtain a "DAC" ?

thanks for your help
 

Sure, you can make a simple RC filter. You need to match the bandwidth with the output frequency of the pulses generated by the delta-sigma modulator, and the needed ripple rejection.

Google a bit around about RC-filters and get some hands-on experience with an oscilloscope and some simple square waves...

If you put two RC-filters after each other, you can generate a 2nd order filter, but the bandwidth calculation is a bit different.
 

thanks for your help... So I can filter the output of the delta sigma modulator to make an analog output, what is the main advantage between delta sigma modulator and PWM + LP filter ?

yes I want to build a DAC not an ADC.

regards
 

if your microcontroller has a pwm, it will be considerable easier to use that.

The sigma-delta modulator will generate a smaller ripple at the same clock frequency.
But if you have an internal pwm in the miucrocontroller, you can use a much higher clock frequency.
 

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