example is an [electronic ballast for fluorescent lamp]. If we would like to
operate the ballast in the close loop, then we would need to know, in order
to design the feedback, the small signal transfer function between the
frequency shift and the envelope changes at the output. The method of
envelope simulation was presented earlier, however, for the sake of clarity,
I will go now over some basic elements. So that we can get into the specific
issues of the present study.