A 95.2% Efficiency DC-DC Boost Converter Using Peak Current Fast Feedback Control (PFFC) for Improved Load Transient Response

The load transient response and unity gain bandwidth of DC-DC boost converters are primarily restricted by the presence of a right half plane zero (RHPZ). In this paper, a control scheme termed peak current fast feedback control (PFFC) is proposed to improve the load transient response without the need for additional power switches or passive components. In the proposed PFFC method, the closed loop output impedance (ZOCL) is improved by reducing the DC value and by increasing the bandwidth of ZOCL as compared to conventional peak current mode control (CPCM), thus improving the steady state and transient performance. The fast feedback (FFB) path is implemented within the error amplifier (EA) with an increase of only 2% in the active area as compared to CPCM. The boost converter is designed for V-OUT = 5V, VIN = 2.5V-4.4V and ILO AD = 10mA-1A operating at a fixed frequency of 2MHz. Measurement results show that with PFFC enabled, the settling time reduces by similar to 2.6 & times; and the undershoot reduces by 62% to 12 & micro;s and 41mV respectively when compared to CPCM for 10mA to 1A load step at 2A/& micro;s. The converter achieves a peak efficiency of 95.2% at 0.5W output power with VIN = 4.4V and load regulation of 9mV/A at V-IN = 2.5V.