Delta Sigma ADC as an averager.

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Anonymous
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 More than an ADC, delta sigma modulator shall very effectively be used as a filter, when the sampling rate is appropriately choosen.

   

When we have an extremely low sampling rate, as low as about 2000SPS, the Sync 4 filter inside the delta sigma adc will strip down the frequency components above 1000 Hz, infact, the sync4  filter has good response to frequencies below 200Hz..

   

So, if you send a stream of pulses to the ADC, we would get the average value of it. 

   

Caution : Choose the range of the ADC Cleverly, as that might result in a poor resolution(here, average value), if not properly choosen.

   

Regards,

   

Rahul ram

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Anonymous
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Remember that BW of sinc4 filter = 0.22 * sample rate instead of classical of 0.5*sample rate

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ETRO_SSN583
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The attached screenshot of the type 2 modulator, CY8C29xxx shows the

   

response for the decimator. Very good point made by rahulram

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ETRO_SSN583
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The attached screenshot of the type 2 modulator, CY8C29xxx shows the

   

response for the decimator. Very good point made by rahulram

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ETRO_SSN583
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Editor blew me out of last post.. I could not find PSOC 3/5 Modulator

   

response curves.

   

 

   

Note additional filter occurs because of finite GBW in input buffer, higher

   

G = lower BW. No surprises here.

   

 

   

Modulator response curves for PSOC 1 type 2 attached.

   

 

   

Regards, Dana.

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Anonymous
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Remember that BW of sinc4 filter = 0.22 * sample rate instead of classical of 0.5*sample rate

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Anonymous
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I learn something new with PSoC everyday 🙂 Thanks RahulRam

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