Chapter 1:

 

                                                                             Fig.1.2

       •  no charge on C for t < 0

  • V in = unit step at t = 0
  • RC small steady state is reached more quickly

We can go for frequency domain analysis to understand this in another way

 

Fig.1.3

Cut off frequency

As RC decreases, increases and circuit becomes capable of handing high frequency - high speed.

So high speed/frequency low RC

Same idea in devices also must reduce RC in devices.

There is a different delay mechanism know as transit time delay. We assume in normal circuits that as soon as the voltage (Electric Field) is applied, current flows immediately in the external circuit. Nature is, however not so kind. The carriers which are influened by the electric field has to start from one terminal of the device and reach the other terminal to show any observable current in the external circuit. Due to finite velocity of the carriers, there is a delay, called the transit time delay as will be explained in the following section.