IIR vs. FIR (complexity issues)

Started by July 18, 2007
Hi,

I would like to know on the implementation complexity issues beween
FIR Filter vs. IIR Filter (Chebyshev).
I know that IIR is more complex than FIR. But, in case of the FIR
filter has higher order number than IIR, FIR can be more complex.

If I have IIR Chebyshev 10th order vs. FIR with 59 Taps. Which one is
the most complex one?


Thanks,

Berry


buzzberry@gmail.com wrote:

> Hi, > > I would like to know on the implementation complexity issues beween > FIR Filter vs. IIR Filter (Chebyshev).
A classic question that was answered by Rabiner. If the goal is having the steepest frequency response and the maximum passband flatness, the IIR filters are more efficient then FIR. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
buzzberry@gmail.com wrote:
> Hi, > > I would like to know on the implementation complexity issues beween > FIR Filter vs. IIR Filter (Chebyshev). > I know that IIR is more complex than FIR. But, in case of the FIR > filter has higher order number than IIR, FIR can be more complex. > > If I have IIR Chebyshev 10th order vs. FIR with 59 Taps. Which one is > the most complex one? >
No matter what you do, the IIR filter code is going to be more complex -- there's just more to do compared to a FIR. Also, IIR filters are significantly more sensitive to coefficient values and quantization effects. A 10th-order Chebychev filter is going to have some highly resonant poles, which will make it even more sensitive. This means that your IIR solution will demand more precision than your FIR, which will add even more complexity to your algorithm. If the book that Vladimir doesn't cover it, I'd recommend that you do some noise sensitivity analysis of your proposed IIR filter, then look at the complexity and execution time of the resulting code to make your decisions. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html