A control system includes a nonlinear delta-sigma modulator, and the
nonlinear delta-sigma modulator includes a nonlinear process model that
models a nonlinear process in a signal processing system, such as a
nonlinear plant. The nonlinear delta-sigma modulator includes a feedback
model that models the nonlinear process being controlled and facilitates
spectral shaping to shift noise out of a baseband in a spectral domain of
a response signal of the nonlinear process. In at least one embodiment,
the nonlinear delta-sigma modulator is part of a control system that
controls power factor correction and output voltage of a switching power
converter. The control system controls the pulse width and period of a
control signal to control power factor correction and the output voltage
level. In at least one embodiment, the nonlinear delta-sigma modulator
generates a signal to control the pulse width of the control signal.