## RC Filters and RL Filters

- RC Low-Pass Filters (links to http://www.mw0llo.com/rc-low-pass-filter.aspx)
- RC High-Pass Filters (links to http://www.mw0llo.com/rc-high-pass-filter.aspx)
- RL Low-Pass Filters (links to http://www.mw0llo.com/rl-low-pass-filter.aspx)
- RL High-Pass Filters (links to http://www.mw0llo.com/rl-high-pass-filter.aspx)

## Standard Filter Designs with Normalised Capacitor and Inductor Values

Standard or "normalised" values are available for filter designs based on the filter type (Chebyshev, Butterworth, Low-Pass, High-Pass etc) and the number of poles (which is usually the number of capacitors \ inductors in the circuit).

These normalised values are given for a cut-off frequency of 1 radian (links to http://www.mw0llo.com/mathematics/circular-measure.aspx) per second (which works out to be approximately 0.159 Hz) and a filter characteristic impedance of 1 Ω.

In order to build a practical filter, it is necessary to transform these normalised values into real values that can be used in the circuit. The equations below show how this is done.

- Inductor Normalisation For Filters (links to http://www.mw0llo.com/inductor-normalisation-for-filters.aspx)
- Capacitor Normalisation For Filters (links to http://www.mw0llo.com/capacitor-normalisation-for-filters.aspx)

## Filter Reference Information

- Butterworth Filter Parameters (links to http://www.mw0llo.com/butterworth-filter-parameters.aspx) - for low pass filters from 1 pole to 10 pole.
- Chebyshev filter parameters fow low pass filters with 0.5dB ripple from 1 pole to 10 pole. (links to http://www.mw0llo.com/chebyshev-0.5dB-filter-parameters.aspx)
- Chebyshev filter parameters fow low pass filters with 3dB ripple from 1 pole to 10 pole. (links to http://www.mw0llo.com/chebyshev-3dB-filter-parameters.aspx)
- Bessel Filter Parameters (links to http://www.mw0llo.com/bessel-filter-parameters.aspx) - for low pass filters from 1 pole to 10 pole.