Use of Threshold Median Adjustment to Achieve Accurate Current Balancing of Interleaved Buck Converter with Constant Frequency Hysteresis Control

This paper proposes a current balancing loop that is obtained using the threshold median adjustment (TMA-CBL) to achieve the accurate current balancing of an interleaved constant frequency hysteresis (CFH) buck converter. The CFH control is implemented with a frequency phase loop based on a threshold width adjustment (TWA-FPL). To ensure the loop’s stability and minimize the steady-state error, a multi-phase, coupled, small-signal model (MPC-SSM) is derived with a consideration of the coupling effect among the multiple phases. Furthermore, the current balancing error is analyzed in detail, with a consideration of the sensing resistance deviations in the loop. Finally, based on a 180 nm BCD process, a four-phase interleaved buck converter is fabricated to verify the effectiveness of the proposed TMA-CBL. The maximum current balancing error is within 0.68% when the sensing resistors are deviated by 5%.