A monolithic CMOS synchronous Buck converter with a fast and low-cost current sensing scheme

Monolithic power management integrated circuit chips are widely used in both consumer products and industrial products. In some applications the load changes drastically. A 2MHz integrated synchronous Buck converter is designed to manage the dynamic load for these applications. The current mode control and active voltage positioning are employed to achieve high transient performance at pulse load conditions. A fast and lossless current sensing scheme with a low-cost, high-voltage-gain and high-bandwidth amplifier configured in open loop is proposed to sense the inductor current for implementing peak current control. With the proposed fast current sensor, the simple first-order compensator is required to obtain active voltage positioning with good stability and transient response. The chip was fabricated with 0.5um CMOS process and the test results were reported.