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The manual is divided into several sections. The first one is about common characteristics for all. The rest of the sections have in-detail descriptions and explanations about the group of filters forming that section. Lastly, there may be additional notes that are characteristic only to the current filter's subcircuit, which will be detailed along with the examples; these are linked here, but opening them might require click-dragging them over an existing opened instance of LTspice, rather than simply clicking on them (which would only make the browser bring up the "Save as..." prompt − only valid for a local copy of the manual).

Note: It is advised not to save the schematics after usage because some can be reused from previous examples and some require user intervention (this is intentionate).
Note: There are cases where there are two simulation cards: one active and one inactive; they can be switched depending on the need. For instance, if the time domain simulation card is active and the frequency domain is not, switching them is done by commenting out the .TRAN card with Ctrl+RClick then 2xClick on the Comment radio button, then uncommenting the .AC card with RClick then 2xClick on the SPICE directive radio button. The reverse is done by the same Ctrl+RClick on the active card and RClick on the inactive one.

Overall, the use of this symbol and its subcircuit is fairly easy once the parameters for each function are known. Updates and changes are ennumerated at the end of the library file; updates of the manual are ennumerated at the end of this html.

Table of contents:


2014.01.25 v1.0
  • Added example for FIR_FS.
  • Corrected list of parameters for FIR_FS.
  • 2014.01.28 Minor corrections/adjustments.
    2014.01.29 Modified Bessel's description to include the phase behaviour modification from filter.sub.
  • Made the whole manual in split html parts and reviewed the examples.
  • Added the new Butterworth_LC and Chebyshev_LC.
  • Corrected the years in the Updates.
  • 2014.01.17 Overall small corrections and fixed links.
    2014.02.24 Minor notes added.
    2014.02.28 Changes in descriptions for AAFs and IIRs to include the modifications from filter.sub.
    2014.03.02 Changes in examples and descriptions for APFs to include the modifications from filter.sub.
  • Corrections/modifications to the text.
  • Added mouse-over descriptions.
  • 2014.04.08 Added History and credits.
    2014.04.16 Corrections/modifications to the text.
    2014.07.30 Modified f0's description for FIRs and IIRs to include the modifications from filter.sub.
    2015.03.29 Updated filter.sub with FIRx and modified accordingly the relevant pages. Corrected IIR's and FIR's external synchronization description.
    2015.03.30 Modified the description for the FIRs to include the modifications from filter.sub. Corrected the description for clock options

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