BS1.4 RC Low Pass Filter/ Integrator

Low Pass Filter


#) Which allow to pass low frequency components and attenuates high 
    frequency components


#) The capacitive reactance Xc=1/(Cx2(pi)f).


#) That is capacitive reactance decreases with increase in frequency


#) Now at the high frequency, the capacitor act as a vertual short circuit which
    directs the input signal to ground thus the output falls to zero


#) At low frequency, Capacitor acts as open circuit, and the entire signal 
    appear at the output

#) By observing above wave form we can see that the Amplitude decreases 

    when frequency increases

Integrator

#) Same circuit can be used as an Integrator

#) An Integrator does the mathematical operation 'Integration' on the input

    signal

#) The time constant RC is very high as compared to time period of input 

    signal

#) When pulse waveform is applied to the circuit, capacitor charges through 

    the resistor abd hence the output voltage buildup

#) When the input is terminated capacitor starts to discharge.

#) Thus we get a Triangular waveform

#) As the value of RC increases amplitude of the output decreases (See above

    fig) because it take more time to charge and discharge