Entering a value for Vin, frequency, R, and C will find the output voltage and phase for the specified values in a first order highpass RC filter. For a first order highpass RL filter, enter a value for Vin, frequency, R, and L. If you don’t enter a value for Vin, a one volt input is assumed.

Unless otherwise specified, the capacitor or inductor tolerance is assumed to be 5%. If you wish to specify a different tolerance, enter it as a percentage (10% = 10).

If you are interested in finding the R & C values for an RC filter, use the solver Passive RC. If you are interested in finding the R & L values in an RL filter, use the solver Passive RL.

For general information about filters, see the Filter Types article. The following equations are used to solve for the values.

The following figure depicts the response of first order passive RC or RL lowpass filter. Although this plot is for a specific corner frequency, all passive first order lowpass filters will have this shape. The only thing that changes is the horizontal (frequency) axis labels.