BS1.5 RC High Pass Filter/ Differentiator

High pass filter

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

    frequency components

#) We know that the capacitive reactance Xc=1/C2(pi)F

#) That is capacitive reactance decreases with increase in frequency

#) Now at the high frequency, the capacitor act as a vertual short, Which

    connect the iput to the output

#) At low frequency, the Capacitor acts as open circuit and it disconnects the

    input and output terminals

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

    when frequency increases

Differentiator


#) Same circuit can be used as an Integrator


#) A Differentiator does the mathematical operation 'Differentiation' on the
    input signal

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


#) The differentiated ouput is propostional to rate of change of input signal


#) If the rate of change of input signal is positive, then the output also 
    positive


#) When input remain maximum or minimum, output remain zero because the 
     rate of change of input is zero


#) Thus we got a Spike Wave form

#) As the value of RC increases amplitude of the output decreases (See the
    fig) because it take more time to charge and discharge