This paper addresses essential features/issues and proposes solutions that would improve the overall performance of a multi-phase buck converter. Low efficiency at light load is addressed with phase shedding, load fast transient and regulated output voltage spiking/dipping is addressed with novel helper technique at the point of load (output node). An Integrated current sensing is utilized to implement over-current-protection (OCP), in addition to its inherent function in current mode control. The phase shedding developed technique was used to enhance the efficiency of the converter. The number of phases rather increases or decreases, depending on the desired load. The proposed fast transient helper circuit is tested by inserting a 500mA transient current step in 100µs. Worst case spike of a 79.1mV was achieved at the output node; which is a reduction of 49.4% of the original response (160mV without the helper circuit). Worst case of a 35mV of output voltage dip was achieved; which is a reduced by 45.4% compared to the original response (77.1mV without the helper circuit). An integrated current sensing technique using current mirroring to equalize the drain voltages of main and replica (sense) PMOS devices was utilized. With this technique, the current in the replica (sense) PMOS device is a scaled down version of the current in the main PMOS device. The sensed currents from all three phases are added up and converted to a voltage. This voltage is compared to a reference voltage that represents the limit for over-current. This reference voltage is set to be 20% higher than the average total currents in the three phases combined.
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