### Impulse Response

In the same way that the impulse response of a digital filter is given
by the inverse *z* transform of its transfer function, the impulse response
of an *analog* filter is given by the inverse *Laplace*
transform of its transfer function, *viz.*,

*Heaviside unit step function*

In more complicated situations, any rational (ratio of
polynomials in ) may be expanded into first-order terms by means of
a *partial fraction expansion* (see §6.8) and each term in
the expansion inverted by inspection as above.

**Next Section:**

The Continuous-Time Impulse

**Previous Section:**

Transfer Function