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Delta Sigma ADC as an averager. | Cypress Semiconductor

Delta Sigma ADC as an averager.

Summary: 5 Replies, Latest post by kmmankad on 19 Dec 2012 07:40 AM PST
Verified Answers: 1
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rahulram's picture
Cypress Employee
115 posts

 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

user_14586677's picture
User
7648 posts

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

response for the decimator. Very good point made by rahulram

user_14586677's picture
User
7648 posts

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

response for the decimator. Very good point made by rahulram

user_14586677's picture
User
7648 posts

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.

PSoC Rocks's picture
User
141 posts

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

user_66945721's picture
User
256 posts

I learn something new with PSoC everyday :) Thanks RahulRam

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