Hybrid Buck

A method for operating a Hybrid Buck switching converter, comprising the steps of:

• providing a Hybrid Buck switching converter comprising peak-mode master or slave phases for low loads and DCM or CCM operation, and valley-mode slave phases for higher loads and CCM operation;
• providing the peak-mode and valley-mode currents of all phases together;
• providing said peak-mode and valley-mode currents with a common operational transconductance amplifier (OTA);
• and
• providing the matching of said peak-mode and valley-mode currents, with a peak current servo, for better efficiency.

A Hybrid Buck switching converter, comprising:

• a transconductance (gm) stage, further comprising:
• an operational transconductance amplifier (OTA) configured to produce a peak current limit, proportional to a DAC reference voltage compared to an output feedback voltage;
• and
• multiple phases, wherein one or more phases operate in peak-mode current control and one or more phases operate in valley-mode current control, each of said phases comprising:
• a peak current servo configured to match said peak-mode and valley-mode currents to said OTA peak current limit;
• matched supply reference currents;
• comparator logic configured to turn the high side device of said peak current servo off;
• control logic configured to modify an offset current to move said peak-mode and valley-mode currents closer to said current limit;
• and
• compensation ramps configured to subtract from said peak-mode current controls and to add to said valley-mode current controls, to prevent sub-harmonic oscillation.