FIG. 1 illustrates a block diagram of a conventional multi-phase DC to DC (direct-current to direct-current) converter such as a two-phase DC to DC converter 100. The DC to DC converter 100 includes two controllers 102, two switching circuits 104, two inductors 108, and an output capacitor 110. Each switching circuit 104 includes a high-side switch Q1 and a low-side switch Q2. In operation, each controller 102 generates a pulse width modulated (PWM) signal to turn on corresponding switches Q1 and Q2 alternately, to cause a ripple inductor current IL through a corresponding inductor 108. Inductor currents IL through the inductors 108 are superimposed to charge the output capacitor 110, to produce an output voltage VOUT at the output capacitor 110. The controllers 102 can control duty cycles of their corresponding PWM signals to regulate the output voltage VOUT.
However, since the DC to DC converter 100 utilizes independent controllers 102 to control duty cycles of the PWM signals, the PWM signals may have different pulse widths caused by differences between the controllers 102. Consequently, the inductor currents IL through the inductors 108 may be unbalanced from each other, which causes error in the output voltage VOUT and reduces performance of the DC to DC converter 100.