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From: rk76073@naakka.tut.fi (Risto Kotalampi)
Newsgroups: comp.dsp
Subject: Re: Phase compensation for IIR filters
Keywords: IIR
Message-ID: <1990Jul10.122121.28209@funet.fi>
Date: 10 Jul 90 12:21:21 GMT
References: <3504@radio.oakhill.UUCP>
Sender: news@funet.fi (#News )
Reply-To: rk76073@naakka.tut.fi (Risto Kotalampi)
Organization: Tampere University of Technology, Finland
Lines: 27


In article <3504@radio.oakhill.UUCP> you write:
>
>I would like to use an IIR filter in a particular application.  I 
>also need linear phase response.  Does anyone have any good references
>to papers/books/chapters concerning digital phase correction for
>IIR filters.  I can't use an FIR in place of the IIR because it is
>a switched capacitor design and must be kept simple.  I CAN however
>use a small FIR or an IIR to digitally correct the phase...additionally,
>the phase ripple can be as high as +-10 degrees and still be considered
>acceptable correction. Any help would be apprieciated.
> 
> -Charlie Thompson

A solution to your problem could be Allpass Filters. With Allpass' you
can design approximately linear phase filters. Some good references :

S.K.Mitra,K. Hirano : Digital All-Pass Networks, IEEE Trans. on
Circuits and Systems, Vol. Cas-21, pp. 688-700, No.5, September 1974.

M.Renfors, T.Saram{ki : A Class of Approximately Linear Phase Digital
Filters Composed of Allpass Subfilters. Was presented at IEEE Int.
Symp. Circuits Syst. (San Jose, CA), May 1986.

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