Fantastic Filter

Fantastic Filter allows the design of common filter types with without out batting an eye. The check buttons are used to make simple specifications and all component values will be calculated, with a schematic of the filter can be placed on the page. This function within SuperSpice is ongoing, so not all features may be available.

Butterworth and Chebychev poles can be calculated to any order. For opamp filters this means any order filter can be built. For LC ladder networks, prototypes up to 17th order have been coded, hence you aint able to do ladder networks bigger then this.

Bessel and Gaussian poles are also hardcoded and restricted to 17th order.

Elliptic filters are in the works.

To access the Fantastic Filter function, press the pink "FF" button or use the view menu item. This will pop up a dialog window with which to setup the filter parameters. Press the calculate button to display the filter data after the desired filter is specified. To place on the schematic page press the "Place button". If other components are on the schematic, this method of placing will update the reference designators on the placed filter to avoid any simulation conflicts. The reference designators of the filter will be kept unmodified when pressing the Edit/Place button. This is so that the filter may be edited and resaved back as a template to make other generic filters. Currently filter schematics are available up to 10th order ladder networks and 10th order opamps. These files are in the c:\Program Files\SuperSpice\System directory with a pretty obvious naming convention. They are in a SuperSpice clipboard format.

There are two types of equivalent ladder network, one with a leading capacitor the other with a leading inductor. These are referenced as CLC and LCL types in the Fantastic Filter setup. The Schematic file names use an "a" or "b" to distinguish them e.g. LCRa_LP2.scl is the Low pass type "a", or CLC type LCR ladder.

Chebychef note: All ladder filters have been set up for equal source and load resistances. This is not actually possible for even order pure Tchebychev or elliptic filters so the "standard" fudge fix has been done to make an almost Chebychev function. The interested reader can look this technique up in the literature, but for those who can't wait it uses the transformations:

and , r = reflection, t = transmission etc…

Editing/Making Larger Template Filter Schematics

1 Use Fantastic Filter to create, either an existing ladder or opamp schematic.

2 Press the Edit/Place button to place the filter on a blank page.

3 Add extra components as desired, noting the obvious naming convention, component values will be ignored, so ignore them

4 Select all components and then cntrl-c (or menu copy command) to copy the schematic to the SuperSpice clipboard.

5 Use the File/Save Current Clipboard menu item.

6 Save in the ..\SuperSpice\System directory with an obvious new name, obtained by looking at all the other file names in that directory for the new filter.

Butterworth - very plain and boring

Chebychev - lots of singing and ringing, much more exciting.

Bessel - It's a procrastinator.

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