Draw the output voltage for the RC differentiator in Figure 20-24.
Draw the output voltage for the RC differentiator in Figure 20-24.
First, calculate the time constant.
\tau =RC= (15 \ k\Omega )(120 \ pF )= 1.8 \ \mu sIn this case,t_{W}\gt 5\tau, so the capacitor reaches full charge before the end of the pulse. On the rising edge, the resistor voltage jumps to +5 V and then decreases exponentially to zero by the end of the pulse. On the falling edge, the resistor voltage jumps to —5 V and then goes back to zero exponentially. The resistor voltage is, of course, the output, and its shape is shown in Figure 20-25.