Capacitors are commonly used to block DC. The capacitor allows the AC frequency to pass while the DC current does not allow the current to pass. The main function of a capacitor is to collect electrical charges. These are reactive components and they respond to low-frequency signals such as DC.
The time when a capacitor is connected in series with a load is known as a coupling capacitor. Coupling capacitors are used where the output of the circuit requires high-frequency signals such as AC in the audio circuit. AC circuits use DC as input and AC as output.
The output of the circuit can be loaded with a capacitor. Also called a loading capacitor. It is also necessary to choose the right capacitor depending on the signal frequency. But the resistance should be connected in parallel with the capacitor.
In today’s article, we will talk about what is Coupling Capacitor, what is its construction and what are its applications, and much more information about Coupling Capacitor.
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What is a Coupling Capacitor?
Definition: A capacitor used to connect the AC signal from one circuit to another is called a coupling capacitor. The main function performed by this is that it transmits the AC signal from one circuit to another but does not allow DC frequency to pass.
This type of capacitor is used in different types of circuits. Such as where only the AC signal is used as output and the DC signal is used to power part of the circuit but it is not used in output.
For example, a capacitor is used in the audio circuit of a microphone. This is given as DC power as input power. But when a user speaks through a microphone, that speech is treated as an AC signal.
The time that the AC signal is supplied from the microphone to the output device cannot pass the DC signal as this signal gives power to the part used in the circuit. And finally, at the output, we get the AC signal. For the same Coupling, Capacitor is used between two circuits.
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Construction of Coupling Capacitor:
A capacitor is nothing but two parallel plates. It is made by filling a dielectric material between these two plates. This allows the AC signal to pass through and blocks the DC signal. Coupling Capacitor is mostly used in analog circuits. While decoupling capacitors are used more and more in digital circuits.
Such a capacitor i.e. Coupling Capacitor can be connected in series with the load for AC coupling. Such a capacitor blocks the low-frequency DC signal and allows the high-frequency AC signal to pass. It reacts differently at different frequencies. This capacitor offers very high resistance for low frequency. Similarly, it offers very low resistance to high-frequency AC signals.
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Calculation Coupling Capacitor:
The capacitor is shorted at high frequency while it is opened at low frequency. The capacitance of a capacitor can be calculated using the following formula.
Xc = 1/2πfc
From the above equation
‘XC’ is a reaction of capacitances.
C = 1 / 2πfXc.
Capacitors Used in Coupling Applications:
Whenever a coupling capacitor is used there are some important points that should be taken into consideration while choosing it. Issues such as series resonance frequency, impedance, and similar series resistance should be kept in mind. The value of capacitance, in particular, depends on the frequency range of the application and the load or ignore of the source.
Different types of capacitors are used inside the coupling capacitor. Such as ceramic, film, tantalum, polymer electrolytic or aluminum organic and aluminum electrolytic capacitors, etc. Tantalum-type capacitors provide high stability for high capacitance values. The cost of this capacitor is higher. Compared to a ceramic capacitor.
Then it has a high ESR. This capacitor is used in coupling applications. Ceramic capacitors are affordable and affordable to everyone and are available in minute SMT packages. Such capacitors are used extensively in RF and audio applications.
Aluminum electrolytic capacitors are compared to low-cost tantalum capacitors. These capacitors have ESR characteristics and give tantalum-related stable capacitances. But this capacitor is large in size. This type of capacitor is used more in connection applications for power amplifiers.
Applications of Coupling Capacitor:
Applications of Coupling Capacitor are as follows:
- This is used in places where only AC signal is required as output and DC signal is used only for certain components to provide power to the circuit.
- This capacitor is used in audio circuits.
- This capacitor is used in PLCC equipment to connect conductive equipment as well as transmission lines.
- This capacitor is used in the substation of power line communication.
- This capacitor is used to connect two phases in BJT so that the O / P of one phase is connected to the I / P of the next phase for amplification.
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