US Patent 7342386 Multiphase power converter having balanced currents

A power converter includes multiple phase circuits, each phase circuit includes a power switch for delivering power to an output of the power converter, a current sensor connected to the power switch for sensing a current in the power switch, a duty cycle controller having an output connected to the current sensor, and a low pass filter connected to the current sensor. The low pass filter is configured to produce a substantially direct current signal proportional to the average current in the power switch. Further, the duty cycle controller is configured to receive the direct current signal and control a duty cycle of the power switch in response to the direct current signal thereby balancing the currents in the phase circuits.