What is Filter Capacitor? Function, Use, Working Principle

Filter, Capacitor, Filter Capacitor, Capacitor as a filter - You have heard so many times these terms if you are an electrical or electronic engineering student. You may want to learn or understand about them more deeply. Or you may have some doubts even after hearing a lot of books, blogs, etc. In this article, we are going to learn about the Capacitor and Filter Concepts as much as possible in a simple way.

First of all, let's know what is capacitor? A capacitor is a passive electronic component that can store electrical energy in the form of charge. The basic construction of a capacitor is, it has two electrodes and a dielectric medium between them.

What is Filter Capacitor?

Any capacitor used for signal filtering purposes can be called a Filter Capacitor. Although, the capacitor is designed for signal filtering only has a little bit different construction than normal power capacitors to ensure its high efficiency but the primary construction of all types of capacitors is the same.

Actually, the term filter capacitor comes from the application of the capacitor. A capacitor can be used for various applications such as energy storage, power factor improvement, tunning, signal filtering, etc. So when it is used for filtering applications then it is called a filter capacitor.

The function of Filter Capacitor

The main function of a filter capacitor is to filter an electrical or electronic signal by bypassing or blocking some components of them. For example, when a capacitor filters a DC signal it removes AC components from that DC signal, or when a capacitor filters an AC signal it removes DC components from that AC signal. When the filter capacitor is used for any processed signal or communicating signal it removes the noise component from that signal by blocking or bypassing them to the ground.

How Filter Capacitor Works?

The simple working concept of a filter capacitor is, it blocks or bypasses the unwanted components from the signal to produce the filtered or pure signal.

Now, the question is how the filter capacitor blocks or bypasses the unwanted components from the signal to be filtered. To understand this principle, first of all, we should know the characteristics of a capacitor.

The main important characteristics of a capacitor are, it blocks DC current and Passes AC current. Capacitive has capacitive reactance which is nothing but the property by which the capacitor block or resist the flow of current through it. The capacitive reactance is inversely proportional to the signal frequency. That means when the frequency is, the capacitive reactance will be low and it will passage more current but when the frequency is low, the capacitive reactance will be high and it will block the current. So, as the AC has frequency it will pass through the capacitor and DC has not any frequency so it will block by the capacitor.

How does the Capacitor filter the DC signal?

To filter the DC signal we need to connect the capacitor in series between the input and output circuit. So when the AC components are available in the DC signal, they will flow through the capacitor(as they have frequency). And as the capacitor is connected in parallel, so the AC components will be grounded through the capacitor, and at the output we will get a pure DC signal. Which type of or how many AC components are to be removed can be decided by the capacitor value.

How does the Capacitor filter the AC signal?

To filter the AC signal we need to connect the capacitor in series between the input and output circuit. So when the AC signal has unwanted DC components applied to this filter circuit, the AC signal will easily pass through the capacitor but the DC components will block as it has not any frequency. Thus we will get a pure AC signal at the output. Here also, which type of or how many DC components are to be removed can be decided by the capacitor value.

Filter Capacitor Uses and Applications

The common applications of filter capacitors are,

1. Rectifier Circuits
2. Inverter Circuits
3. Audio Processing Circuit
4. Telecommunication Circuit
5. Signal Processing Circuits
6. Voltage regulator circuits

Read Also: 

• What is AC Capacitor? Ratings, Applications, Properties
• What is Y Capacitor? Applications, Uses, Values
• Shunt Capacitor Use, Applications, Advantages
• [Actual] Difference Between Capacitor and Condenser
• When Capacitor store more Energy Series or Parallel connection?

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