Abstract: A current-sensing circuit using senseFETs as current sensing devices in a current mode PWM DC-DC Converter system is presented.It is easy to be integrated because of the simple structure and it owns excellent frequency response, low power dissipation.The accuracy of this circuit is high in a wide range of the load current，and it will be elevated with the using of the cascade-common-gate amplifiers' structure.The test chip is fabricated in CSMC 0.5 μm 2p3M 3.3 V CMOS process.The measurement results show that the buck converter can operate from 1.2 to 2 MHz with supply voltage from 2.5 to 5.5 V for lithium ion battery application，and the output voltage is 1.5 V.The highest accuracy of proposed current sensing circuit is 97.75% for the load current from 50 to 600 mA.

Key words: current-sensing, current-mode, SMPC, common-gate-amplifier, sensing resistor, senseFET

摘要： 提出一种应用于电流模的PWMDC-DC转换器系统、利用senseFET作电流检测器件的新颖的电流检测电路。该电路结构简单，易于集成，具有功耗低、频率特性好、响应速度快、不降低电源系统的工作效率等优点。同时，该电路在很大的负载电流范围内实现高精度的电流检测功能。芯片利用CSMC0.5μm 2p3M 3.3V CMOS工艺实现。这款降压芯片能够在1.2～2MHz的频率范围内将输入的2.5～5.5V的直流电源电压转换为1.5V的稳定直流电压输出，完全适用于单节锂电池电源的系统。在50～600mA的负载电流范围内，测试检测电流的精度最高可达到97.75%。

关键词: 电流检测, 电流模, SMPC, 共栅放大器, 检测电阻, 检测晶体管