Abstract: A novel integrated CMOS current-sensing circuit for current-mode DC-DC buck converters is presented.The circuit is concise and simple to implement,and the power loss is low.Also,the achieved sense ratio is almost independent of temperature,model,and supply voltage after matching the MOSFETs.Through optimization,the response speed is faster and the minimum input voltage is lower.A current-mode DC-DC buck converter with the proposed structure has been fabricated in a 0.5μm CMOS process for validation.With a 2.5~5.5V input range,the chip works steadily in the load current range of 0~2A.It has a good transient response and the measured maximum efficiency is up to 96%.

Key words: DC-DC buck converter, current-mode control, current-sensing circuit