What is a Filter Capacitor? | Filter Capacitor Working and Applications

The Filter Capacitor is the basic type of capacitor there is no difference from the other capacitors, it depends on the type of working. The capacitor is a reactive component used in analog electronic filters due to the function of the capacitor’s impedance frequency. Depending on the frequency of the capacitor that affects the signal. This property is therefore widely used in the design of filters. Analog electronic filters such as LPF can be used to perform a predefined signal processing function.

Capacitor Images

Filter Capacitor

The main function of this filter is to allow low frequencies and avoid high frequencies. Likewise, HPF allows high frequencies and inhibits low frequencies. An electronic filter can be made using analog components such as resistors, capacitors, transistors, operational amplifiers, and inductors. This article provides an overview of the filter capacitor and how it works.

Read Also: What is a Coupling Capacitor | Applications of Coupling Capacitor

What is a Filter Capacitor?

The capacitor used to filter a specific frequency is called a filter capacitor, which is a series of frequencies in the electronic circuit. Typically, a capacitor filters low-frequency signals. The frequency value of these signals is close to 0 Hz, also called DC signals. This capacitor is therefore used to filter out unwanted frequencies. They are very common in a wide variety of devices such as electronics and electricity and are applicable in a variety of applications.

Filter Capacitor Working

This capacitor works on the principle of capacitive reactance. Capacitive reactance means that the impedance value of a particular capacitor varies depending on the frequency signals flowing through the respective capacitor. Take the example of a resistor in a circuit. The resistance of the device does not change, it provides the same resistance depending on its constant value. But a capacitor has a variable capacity. The capacitance is affected due to the applied frequency value of the signals.

The work of this capacitor is mainly based on the principle of capacitive reactance. The impedance of a capacitor is nothing more than how it changes with the frequency of the signal passing through it. A non-reactive component such as a resistor provides resistance equal to the signal rather than the frequency of the signal. This means that the 1Hz and 100KHZ signals pass through the resistor with equal resistance.

But, impedance or resistance is different from a capacitor, it will change based on the signal frequency which is flowing through in it. They are reactive devices that provide high resistance to low-frequency signals and low resistance to high-frequency signals using a formula such as XC = 1 / 2πfc. A capacitor gives unequal impedance values for an unbalanced frequency signal. In the circuit, it can act as a resistor.

Read Also: Types of Diodes | Applications of Diodes | Rectifier, Clipper, Reverse Current Protection

Filter Capacitor Formula

The filter Capacitor is widely used in power supply circuits, which is for reducing ripple at the output.

The formula is C = I / 2f Vpp

the above formula I is the load current, f is the input frequency and Vpp is the minimum ripple that may be acceptable.

= 1/2* 3.14* f c

where Xc is the capacitive reactance.

Capacitor Symbol

Capcitor Symbol

Capacitor Symbol

Filter Capacitor Circuit To Block DC and Pass AC

It has already been discussed that it offers low resistance compared to high-frequency signals and high resistance compared to low-frequency signals. To avoid the direct current DC, we must give priority to high-frequency signal transmission. In this case, the designed circuit acts as a high pass filter.

Filter capacitor Circuit

Filter Capacitor Circuit Diagram

Several times in a circuit, the DC and AC signals must be used at at least one stage of the circuit. However, in another step, in the circuit, we may only want to pick up AC and DC signals. A microphone circuit is one example. We need DC power as input to turn ON the microphone and we need AC power as input, which indicates the voice signal or music that the microphone wants to record.

Filter Capacitor Applications

Applications of filter capacitors are,

  • Filter Capacitors can be used for the design of high pass filters, low pass filters, etc…
  • The capacitor can be connected after the voltage regulator to reduce ripple in the DC power supply.
  • capacitor most widely used in audio, IF, or RF filters.
  • It is preferred in the processing of signals.
  • These capacitors are used for glitch removal on DC power rails.
  • protective circuits where the concern is about heavy loads such as air conditioners and refrigerators.

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