
Principles of Analog Electronics
248
so we obtain an output voltage that is proportional to the input integral (remember
the Laplace transform from time to frequency domain:
j
⇔
) when
jwRC RC w
f
1
=ω >> ⇒>>⇒>>
Therefore this RC circuit performs the function of integration better and better
as the frequency is larger than
(the gray area in Figure 7.32), which is
exactly the cutoff frequency of thecircuit.
Analyzing the graph, we gather that the circuit behaves as an integrator only
when the output voltage is a fraction of the input one. It would be useful then to
combine an amplication circuit (i.e., a circuit that increases ...