Method and circuit for automatic correction of emulated inductor current
without knowledge of actual inductor current ramp for an emulated current
mode (ECM) PWM switching regulator. In an ECM-PWM switching regulator a
compensation ramp component is usually added to an up-slope. An excess
ramp component may also be added compared to actual inductor current.
According to one embodiment of the present invention, an integrating
negative feedback circuit is employed to reduce both extra components.
According to another embodiment, a single integrating negative feedback
loop is added to the ECM-PWM regulator to retain the compensation ramp
component while reducing the excess ramp component. According to a
further embodiment, excess ramp component is reduced by adding the
integrating negative feedback loop at an end stage of the circuit.
Finally, the feedback loop with two duplicate track-and-hold circuitry
may be added to reduce the excess ramp component, while retaining the
compensation component.