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Design >> Analog Design >> How to analyze relationship between filter group delay and receiver performance?
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Message started by tulip on Sep 3^rd, 2009, 12:18am

Title: How to analyze relationship between filter group delay and receiver performance?
Post by tulip on Sep 3^rd, 2009, 12:18am

I am designing a filter in a receiver system.

What I need to know is : what is the relationship between the filter's
group delay and system performance?

Filter's group delay can induce signal distortion, our receiver system
has the design target of SNR, IIP3 and so on, but how these design
targets can be related to filter's group delay?

I tried to use ADS to get the relationship, I put a cauer filter in the
system, first I think I can find the distortion by substract the output
signal of filter from the input signal of the filter, but because the delay
between the input and output signal, they can not be direct substracted.

What can I do to analyze the relationship between filter's group delay and receiver performance?

Thank you very much.

Title: Re: How to analyze relationship between filter group delay and receiver performance?
Post by buddypoor on Sep 3^rd, 2009, 2:01am

I don´t think you will find any relationship (formula) between group delay and those performance parameters mentioned.
My first idea is to use a filter with no resp. very little group delay (Bessel-Thomson characteristics) and than replace it with another filter of your choice in order to evaluate the quality change.

Title: Re: How to analyze relationship between filter group delay and receiver performance?
Post by aaron_do on Sep 4^th, 2009, 9:06am

Hi,

I read somewhere that the rule of thumb is that the group delay variation should be less than 10% of your symbol period. However, I can't find the reference.

But anyway you probably need to see the effect of the GD on the BER. I suggest some kind of behavioural simulation in Matlab. I believe your GD requirement depends heavily on the modulation scheme chosen as certain modulation schemes pack a lot of throughput into the signal bandwidth. As buddypoor mentioned, you probably won't see GD affecting NF, IIP3, etc.

cheers,
Aaron

Title: Re: How to analyze relationship between filter group delay and receiver performance?
Post by tulip on Sep 8^th, 2009, 4:07pm

Thank you very much.