A 25MHz Dual-Phase Buck Converter Using Full-Differential High-Gain Current Balance Method with Chopper and Notch Filter

This paper presents a ZDS hysteretic 25MHz dual-phase DC-DC buck converter for large current point-of-load (POL) application. To realize current balance, average current sensing technique with chopper and notch filter and full-differential high-gain (FDHG) current balance method are introduced in the hysteretic controller. The proposed method senses average inductor current by the drop voltage across the inductor’s DCR and uses chopper technique and notch filter to realize high precision detection. The FDHG current balance scheme then eliminates the inductor current mismatch between two phases effectively. The 25MHz dual-phase ZDS hysteretic buck converter was designed in 0.18μm CMOS process. Accurate current balance is achieved, and the converter supports the full load of 3A and achieves the peak power efficiency of 83.3%.