Harmonic Balance Analysis-lecture notes
Harmonic Balance Analysis
Harmonic balance is a non-linear, frequency-domain, steady-state simulation. The voltage and current sources create discrete frequencies resulting in a spectrum of discrete frequencies at every node in the circuit. Linear circuit components are solely modeled in frequency domain. Non-linear components are modeled in time domain and Fourier-transformed before each solving step. The informations in this chapter are taken from  (chapter 3) which is a very nice and well-written publication on this topic.
The harmonic balance simulation is ideal for situations where transient simulation methods are problematic. These are:
components modeled in frequency domain, for instance (dispersive) transmission lines
circuit time constants large compared to period of simulation frequency
circuits with lots of reactive components
Harmonic balance methods, therefore, are the best choice for most microwave circuits excited with sinusoidal signals (e.g. mixers, power amplifiers).
The Basic Concept
Going through each Step
Creating Transadmittance Matrix
A Symbolic HB Algorithm
Large-Signal S-Parameter Simulation
Autonomous Harmonic Balance