Multiple-loop control of DC-DC converters

A switching voltage regulator must show high efficiency, good regulation, low output-voltage ripple, and also stability and fast transient response. The use of additional feedback signal(s) from the inductance currents and capacitor voltages keeps the overall phase shift of the control-to-composite-feedback transfer function lower than -π/2. The error amplifier can be built to add only -π/2 phase shift and thus the switching power supply becomes unconditionally stable can have much faster transient response than single-feedback regulator. Another key condition for the stability of double dc-dc converters is the first-section LC-circuit damping.