# Operation of the Filter

The operation of the high-pass filter can be verified from the gainâ€“magnitude equation as follows:

- At very low frequencies, i.e.,
*f*<*f*, <_{c}*A*_{F}

**High pass filter characteristics**

- At
*f*=*f*, = = 0.707_{c}*A*= â€“3 dB,_{F}*Ï†*= 45Â° - At
*f*>>*f*_{c}, â‰…*A*_{F}

# Filter Design

A high-pass active filter can be designed by implementing the following steps:

- A value of the cut-off frequency,
*Ï‰*(or_{c}*f*) is chosen._{c} - A value of the capacitance
*C*, usually between 0.001 and 0.1 ÂµF, is selected. - The value of the resistance
*R*is calculated using the relation,*R*= = - Finally, the values of
*R*_{1 }and*R*are selected depending on the desired pass-band gain, using, the relation,_{f}*A*= ._{F}