The Passive Filter Instructions

This is a UK site and uses UK English terminology. Metric is the system used, though there are concessions to the usage of oz and mils where mentioned. Otherwise a metric system and metric dimensions are used. The results and Pdf's are always in metric. In general the dimensions in use are given on the data entry forms.

General Dimensions

Numbers are integer or decimal format, with use of the '.' as delimiter.

Frequency is any decimal number with or without postfix ie: 120.5 or 120.5Hz, 10.4GHz, 48KHz etc...

Ohmic Terminations are decimal quantities eg: 50.0, 27K, 2.2M

Capacitors and Inductors are presented in selection tables scaled to the E series precision of the design.

Physical dimensions are always in mm, except for thickness's, here oz and mils can usually be used because of the common usage.


Run down the click buttons to get to the Filter type required. eg: A passive Linear Phase.

Fill in the data for the filter specification, following the guide lines above.

Click calculate to generate the scaled filter component values. The Calculation correct message appears. The required filter order can be calculated. Sometimes for the elliptical and Chebychev type 11 filters the components become too precise or disparate in values, so using the order calculation the attenuation cut-off point can be adjusted easily.

The filter response is choosen from the tabs. The table tab allows the global Q values, tolerances to be set and the individual component parasitic values by using the dit link in the tables. On the design tab the design can be saved in a temporary store.

Looking along design page tabs there is a More... tab. This allows extended analysis of the filter for the voltages, currents and power dissipation of the filter components. Especially usefull for power filter desgn. Some frequency ranges allow access to a catalog of inductors and capacitors, these are attached to analysis models so the filter can be analysed using practical components.

There is a pdf button so once a design is acceptable the components, response can be downloaded in pdf format.