+ Post New Thread
Results 1 to 4 of 4

17th July 2011, 07:53 #1
 Join Date
 Jun 2006
 Posts
 84
 Helped
 0 / 0
 Points
 1,677
 Level
 9
delta sigma cic filter
about delta sigma cic filter
it consists of integrator , decimator and differentiator.
lots of thesis discuss the mininmun word length for preventing overflow.
and it says that it is the same as the average window filter in frequency domain.
but if we disuss it in transient domain?
since every integrator in each stage will overflow
because each integrator is an accumulator , it will accumulate the past result from "t=0" , it means
it will rapidly overflow anyway ..except the wordlength is infinite.
i don't know if my concept is right or wrong ,
since if it will overflow in the first stage , it will saturate on the next stage and faster than first stage .. the cic will behave wrong.

Advertisment

17th July 2011, 09:01 #2
 Join Date
 Apr 2008
 Location
 villingen (Germany) / Bangalore
 Posts
 5,070
 Helped
 2157 / 2157
 Points
 33,613
 Level
 44
 Blog Entries
 1
Re: delta sigma cic filter
" It is so simple to be happy,
but it is so difficult to be simple"
1 members found this post helpful.

Advertisment

17th July 2011, 10:45 #3
 Join Date
 Jan 2008
 Location
 Bochum, Germany
 Posts
 43,801
 Helped
 13318 / 13318
 Points
 251,460
 Level
 100
Re: delta sigma cic filter
lots of thesis discuss the mininmun word length for preventing overflow.
and it says that it is the same as the average window filter in frequency domain.
As a simple exercise, you can evaluate CIC behaviour with pencil and paper, or more easily, with a spreadsheet calculator.
The analogy with a moving average filter applies to the first order CIC decimator. The interesting point, and perhaps not obvious at first sigth, is that it can be extended to higher orders and still keep the signal average, although all integrators are continuously overflowing.
The best description of CIC filters is still the original Hogenauer paper An economical class of digital filters for decimation and interpolation, although the mathematical part is somewhat demanding.
Some aspects of CIC filters have been discussed in previous edaboard threads, e.g. https://www.edaboard.com/thread127067.html
1 members found this post helpful.

Advertisment

1st December 2014, 13:19 #4
 Join Date
 Apr 2010
 Location
 jaipur
 Posts
 169
 Helped
 1 / 1
 Points
 2,230
 Level
 10
+ Post New Thread
Please login