Some design consideration of switching regulator using current-injected control

Open-loop stability analysis of multi-loop current-injected switching regulator is performed using a small signal model containing a power stage, an error processor and a duty cycle pulse modulator. Two design constraints and the effects of various critical control circuit parameters are pinpointed and the analysis-based design guidelines are established in order to optimize the switching regulator performances.

In addition, an external ramp slope is proposed to obtain the optimal performance and eliminate the 50% duty cycle instability when operated in constant frequency mode. The effects of the second stage output filter are also examined.