Intermodulation noise related to THD in wide-band amplifiers

It is shown that the power of the intermodulation noise of a wide-band amplifier with a Gaussian input signal, can be estimated by the total harmonic distortion (THD) with a sinusoid input signal of appropriate amplitude. The THD is, as opposed to the intermodulation noise, easy to measure and use as a design parameter. A novel method based on probability density functions is used. The method is demonstrated by a practical example, and a mathematical experiment is carried out to validate it.