Pulse and Digital Circuits

2.3 DIFFERENTIATORS

Sometimes, a square wave may need to be converted into sharp positive and negative spikes (pulses of short duration). By eliminating the positive spikes, we can generate a train of negative spikes and vice-versa. The pulses so generated may be used to trigger a multivibrator. In such cases, a differentiator is used. If in a circuit, the output is a differential of the input signal, then the circuit is called a differentiator.

2.3.1 A High-pass RC Circuit as a Differentiator

If the time constant of the high-pass RC circuit, shown in Fig. 2.1(a), is much smaller than the time period of the input signal, then the circuit behaves as a differentiator. If T is to be large when compared to τ, then the frequency must be small. At ...