A new single-inductor quadratic buck converter using average-current-mode control without slope-compensation

Abstract

A new single-inductor quadratic buck converter using average-current-mode control without slope-compensation is proposed in this paper. The average-current-mode technology minimizes several power-management problems, such as efficiency, EMI, size, transient response, design complexity, and cost. In DC/DC conversion applications that require a wide range of input and/or output voltages, conventional PWM buck converter topologies always operate at exceptionally low duty ratios, which limit the operation to the lower switching frequencies due to minimum ON-time of the transistor switch. The DC voltage conversion ratio of the proposed converter has a quadratic dependence on duty cycle, producing an extensive step-down; therefore, the high conversion ratio is achieved. This scheme employs an inner loop for current gain and an outer loop for PID-controller. The proposed buck converter only uses an inductor, two capacitors and single control circuit to achieve quadratic conversion ratio, therefore, an inductor and a control circuit is reduced. The advantages of the proposed quadratic buck converter are fast transient response, no use for slope-compensation, high-conversion-ratio, and an inductor reduction. The prototype of the proposed quadratic buck converter has been fabricated with TSMC 0.35µm 2P4M CMOS processes. The total chip area is 1.917 × 2.334 mm2.