Here an active 2nd order high pass filter(HPF) design using LM358 operational amplifier is illustrated. The HPF is build on a breadboard. It has a cutoff frequency of 1kHz. The active filter designed is tested and filtering action is illustrated. The filtering action shows that the amplitude of the input signal at the output increases as the frequency is increased from lower 0Hz to upper frequency such as 10kHz. The frequency response graph of the designed filter is also illustrated.

**Recommended Prerequisites**

- Active 2nd order LPF on breadboard
- Active 1st Order Low Pass Filter Design on Breadboard
- First order Active HPF Design and Test

### Video

The following video shows the designed filter and testing of the filter.

### 2nd order HPF on breadboard

The following picture shows the active high pass filter build on a breadboard.

### Circuit Diagram of 2nd order active HPF

The following shows the circuit drawing of the 2nd order active high pass filter that was build on the breadboard shown above.

The 2nd order high pass filter shown above consist of two RC filters. The first is made up of R1 and C1 and the second is made up of R2 and C2. The cutoff frequency of the HPF is given by the following equation.

_{1}= R

_{2}= R. Similarly we can set the capacitors C1 and C2 equal. That is let C

_{1}= C

_{2}= C. With this simplification, the above cutoff frequency formula can be written as,

_{1}= R

_{2}=15kohm and C

_{1}= C

_{2}= 0.01uF which gives cutoff frequency of 1khz.

_{F}get is set by the resistors R

_{F}and R

_{3}.

_{F}should be 1.586. Doing so we can calculate the value of R

_{F}by selecting R

_{3}.

_{3}=10kohm and with A

_{F}= 1.586 we get R

_{F}=5.86 KOhm.