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Altera_Forum's avatar
Altera_Forum
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15 years ago

matlab code of 8 order iir using 2 order cascade

Hi friends

I am new in this forum and hope u will help me to find the solution of my problem. I need to write the matlab code of 8 order iir band pass filter using 2 order cascade without house keeping problem.pls take any example and send me the code.For ex i have the 24 second order coeffiecients to design 8 order band pass filter.

1. also tell me which structure will be better

a. TDA(numerator-denominator)

b. TDA(denominator-numerator)

c.TDL(numerator-denominator)

TDL(denominator-numerator)

Thanks and regards to all

anubhav seeking for help

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    This is an FPGA forum, not a Matlab forum.

    Besides that, your problem is extremely trivial. Just google for it.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    take your coefficients generated from matlab and perform roots(a) and then roots(b) to derive conjugate pairs. Then poly(a(1:2)) poly(a(3:4)) etc and same for "b". Then match your pairs for optimal shape and lowest noise gain in your system. Then scale so that coeffcients normalised - this may require an extra add with respect to "A"s if any greater than "1" (you will find out what I mean when you try), whereas B can be scaled together. Then chose biquadratic strategy that matches your requirements ... I suggest you research Transpose forms 1 and 2. Try to find one with lowest "summer node" gain.

    Now only thing remotely related to FPGA ... good lucj with fxed point ... make sure you properly analyse your filter with respect to stability and regenerative noise gain. FPGAs are not floating point.