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Design consideration of CMOS anti aliasing filter

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Junus2012

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Dear friends,

I am starting with the design of a fully differential anti aliasing filter,
my maximum input signal bandwidth is 5 MHz.

I never worked with filter design,

1. it will be useful to suggest me some text or good papers regarding this type of filter, what is the best filter topology to implement (like Sallen key ...etc)

2. Is there any difference between low pass filter from anti-aliasing filter ? like some extra consideration must be specifically taken for AAF

3. what should be the GBW of my CMOS fully differential amplifier to process accurately the targeted input signal


Any help will be appreciated

Thank you
 

FvM

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1. Filter design starts with the specification, pass- and stop band requirements, resulting filter order. Sallen key is surely a candidate, MFB may be advantageous for fully differential implementation.

2. Not particularly. Anti-aliasing filter requirements can be quite different. Low order and relaxed spec for oversampling ADC, high order and tight spec for signal bandwidth near the Nyquist frequency.

3. Rule of thumb says GBW >= 10* filter frequency, at least for low and medium pole pair Q. Filter dimensioning may need adjustment for finite GBW, good filter design tools will do.
 

Junus2012

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Thank you FvM for you nice answer, I am sencierely garteful to your continous support,
I need to have a look on your answer before I go in further discussion

Thank you once again
 

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