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    Home  -  News  -  Industry News

    What makes FIR filter digital quality better?

    source:Industry News release time:2022-10-28 Hits:     Popular:Infrared sensing module

      

      Lack of feedback is key. When the FIR filter is implemented in the computer, every calculation produces a digital error. Since the FIR filter has no feedback, it cannot remember previous errors. Conversely, feedback from the IIR filter can lead to an accumulation of errors. The practical effect is that a filter with the same precision as an IIR filter can be achieved with fewer bits. For example, while FIR filters are usually implemented with 16 bits, IIR filters usually require 32 bits or more.

      Because only a small part of the calculation needs to be done with subsampling or interpolation filters.

      Since FIR filters do not use feedback, only those outputs that are actually needed need to be computed. For example, in subsampling (where only one of the N outputs is valid), the other N − 1 outputs are not evaluated. Similarly, for interpolation filters (inserting zeros in the sampling points to improve the sampling rate), you don't have to actually multiply the coefficients by the FIR filter and sum them up, you just have to ignore the multiplications associated with these values (because they don't change the result).

      In contrast, because IIR filters use feedback, every input must be used and every input must be computed because all inputs and outputs have an effect on the feedback of the filter.


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