Modified Sine Wave Filter Series Loop And

Low Pass Filter is a filter which will pass only low frequency signals and attenuate high frequency signals.

This cut off frequency value will depends on the value of the components used in the circuit.

The cut off frequency is also called as break frequency or turn over frequency.

Passive Low Pass Filter The Low Pass Filter circuit which is designed by passive components is referred as passive low pass filter.

Resistor is independent to the variations of the applied frequencies in the circuit but capacitor is a sensitive component that means which responds to the changes in the circuit.

Since it has only one reactive component this circuit can also termed as one pole filter or First order filter.

Modified Sine Wave Filter Series Loop And

The input voltage Vin is applied to whole series loop and the output voltage is taken only across the capacitor.

Since capacitor is a sensitive component the main concentration to be observed is about capacitive reactance.

Capacitive reactance is the opposition response created due to the capacitor in the circuit.

In order to maintain the capacitance of the capacitor, the capacitor will oppose a small amount of current flow in the circuit.

This opposition to the current flow in the circuit is called impedance.

Thus the capacitive reactance decreases with increase of opposing current.

By this we can say that the capacitive reactance is inversely proportional to the frequency applied to the circuit.

The resistive value of the resistor is stable whereas the capacitive reactance value varies.

This means at low frequencies the voltage drop is small and the voltage potential is large but at high frequencies the voltage drop is very high and the voltage potential is less.

By this phenomenon we can say that the above circuit can acts as a frequency variable voltage divider circuit.

By using these terms we can formulate the equation for RC potential divider equation as follows.

Low Pass Filter Example Let us examine these output voltage values and capacitive reactance values by considering the resistor and capacitor values.

Let the value of the resistor R is 4.7k and capacitor value as 47nF.

The frequency values for which we are going to calculate are at 1 kHz and 10 kHz.

Not only the capacitive reactance but also the output voltage decreases.

From the above example it is observed that the capacitive reactance is decreased from 3386.27 ohms to 338.62 ohms, whereas the output voltage decreased from 5.84 volts to 0.718 volts with the increase of the frequency from 1 kHz to 10 kHz.