Once a harmonic balance simulation is solved a cyclostationary noise analysis can be performed. This results in the sideband noise of each harmonic (including DC, i.e. base band noise). The method described here is based on the principle of small-signal noise. That is, the noise power is assumed small enough (compared to the signal power and its harmonics) to neglect the higher order mixing products. This procedure is the standard concept in CAE and allows for a quite simple and time-saving algorithm: Use the Jacobian to calculate a conversion matrix and then apply the noise correlation matrix to it. Two important publications for HB noise simulation exist that were used for the next subsection , .
Figure 8.1 shows the equivalent circuit for starting the HB noise analysis. At every connection between linear and non-linear subcircuit, there are two noise current sources: one stemming from the linear subcircuit and one stemming from the non-linear subcircuit.