A boost switching regulator incorporates a ripple injection circuit to generate a voltage ripple signal for feedback control that mimics the actual ripple signal of the regulated output voltage. In this manner, the ripple injection circuit achieves optimal ripple injection for stable and enhanced feedback control. In one embodiment, the injected ripple signal is generated from a current injection signal that mimics the difference between the inductor current that flows through the synchronous rectifier and the load current when the synchronous rectifier is on. The injected voltage ripple signal is generated when the current injection signal is integrated by a feedforward capacitor.