What is a High Pass Filter?

As the name suggests, a high pass filter acts as a filter to impede low-frequency signals and helps high-frequency signals pass through quickly.

So, in technical terms, high pass filters are used to filter out low-frequency signals so that you will only receive high-frequency alerts through it. The filtering process of high pass filters depends on a few factors and components. Depending on your given frequency, the input of these components can either go up or down.

In this article, we’ll break down everything you need to know considering high pass filters so that you can finally have your answer of what is a high pass filter.

Factors Considering High Pass Filter

High pass filters follow a few characteristics that define how the filter works. These are:

Cutoff Frequency

Cutoff frequency stands for the amount of frequency that is required to pass through high pass filters.

In technical terms, the cutoff frequency is described as the boundary in a system’s frequency response. When the frequency reaches this point, it starts to get reduced or blocked instead of passing through. Without cutoff frequency, circuits consisting of high pass filters wouldn’t exist.

Filter Slope

The filter slope can be described as the definition of how fast frequencies get reduced once they go through the cutoff frequency limit. Usually, it can be found in the dB/octave figure. The standard filter slope is said to be around in 3dB cutoff frequency.

Function Generator

Function generators are a sort of signal generator that can generate a continuous amount of waveform of various shapes and sizes. It can also be used as a device that will apply DC offset to your signals. To build high pass filters, it is necessary to have a function generator.

Capacitor

A capacitor is an electrical component that is commonly used to store energy in an electronic field.  To function, a circuit capacitor is a necessary component.

Resistor

The resistor provides resistance in a circuit. It provides blockades in the flowing current in a course and is one of the most commonly used items when building any sort of electric circuits and is a crucial component for high pass filters circuits.

Inductor

An inductor is a two-wired device that takes the flowing electricity on a circuit and stores the electricity as magnetic energy. It is capable of generating a magnetic field is required.

Types of High Pass Filters

High pass filters are found in different types, but on a standard basis, high pass filters can be divided into two types:

• High Pass RC Filter
• High Pass RL Filter

These filters can also be broken down into two different types, but the core feature stays the same.

High Pass RC Filter

A high pass filter will be regarded as a high pass RC filter if the resistor and capacitor are connected in a series connection. A high pass RC filter is susceptible to lower frequencies and DC inputs.

Therefore, it reduces frequencies that don’t meet the cutoff frequency point and don’t allow DC signals to pass through.  As it blocks the DC output, many refer to it as a coupling capacitor as it couples up the AC signal and let it flow from one part of the circuit to another while blocking the DC signal all the time.

Types of High Pass RC Filters

High pass RC filters can be broken down into two types of filters:

• Passive RC High Pass Filters: This type of RC filter is built with passive elements, which means that this type of high pass filters don’t require external power to power up the filter.
• Active RC High Pass Filters: As the name suggests, an active RC filter needs an active power source to function; you will still need the passive elements like the capacitor and resistor, but you need to add an extra Op-amp an active power source.

Example of A High Pass RC Filters

A great example of a high pass RC filter is microphones. If we look into microphone circuits, it shows the same classification for high pass RC filters. A microphone circuit requires both AC and DC power signals, but AC is required to give your vocal or sound output while DC is only needed for power.

So, the circuit blocks the DC signal and blocks low frequencies; thus, your mic output sounds excellent as it now has the high frequencies and AC signals as output.

High Pass RL Filter

A high pass RL filter is composed of elements like an inductor, resistor and can only be created if the inductor in parallel with the power source.

These high pass filters work on the complete opposite of RC filters. This filter in the circuit allows the low-frequency signals to move freely while providing great resistance to high-frequency signals and nullifying them afterward.

Now you might question if the high frequencies can’t get past the inductor; how is this a high pass filter? Because electricity runs through the easiest path possible.

If the high-frequency signal faces excellent resistance by going through the inductor, it will skip going through the inductor and go in an alternate way that is direct to the output.

Therefore, you’ll receive high-frequency signals faster, thus completing a high pass filter requirement.

Applications of High Pass Filter

High pass filters are used in the following sectors:

• High pass filters are widely used to enhance sound qualities by removing low-end buzz noise and providing smooth high-frequency sounds.
• High pass filters are used as amplifiers in speakers, which also serves as a safeguard by blocking DC signals, thus saving the speaker from internal circuit damage.
• For image processing and sharpening, high pass filters are used for better enhancement and clarity.

Conclusion

High pass filters are essential for getting high-frequency outputs without having to worry about low-frequency signals. It serves an excellent purpose for enhancing the sound quality of objects. Hopefully, this article has helped you understand high pass filters so that you can find the best use of them if you need to work with high pass filters in the future.

You may also like to read: High Pass vs. Low Pass Filter: Which One is Perfect for you?