Some consideration needs to be addressed for the test signal chosen to evaluate the transient response of a linear system. By the properties of Laplace transforms， if a unit impulse input is used and the measured output response is integrated， the result of applying an inverse Laplace transform will yield the systems frequency response. This approach is not typically useful since pulse generators do not generate impulses and the integration becomes unduly complex. Additionally， this technique does not serve to establish an intuitive feel. Alternatively， if a slowly time-varying input signal is used as the test input， the high-frequency components in the system are not significantly excited. The step response often provides a meaningful evaluation of amplifier performance， and represents a more practical signal. Other advantages of using a step response is that it directly provides the dc gain， and the high-frequency nature of the step excites the high-frequency poles in the amplifier’s system transfer function.