300 mA快速瞬态响应的无电容型LDO设计

A 300 mA capacitor-less LDO with fast-transient response

为满足多负载供电应用下大电流输出与快速瞬态响应要求,同时降低外围组件的成本,提出一种具有300 mA电流输出能力的、无片外电容型低压差线性稳压器(LDO)。采用主极点频率补偿技术,将主极点位置移至稳压器内部,克服了传统LDO的频率稳定性对片外电容的依赖。稳压环路采用了双环路控制结构,即由四级放大电路构成的高增益主环路,保证了输出电压的精度要求;由高速共栅放大电路构成的快速瞬态响应环路,实现了对输出电压的快速响应。电路基于5 V 0.35μm CMOS工艺设计并流片。仿真及测试结果表明,负载电流为0~300 mA、输出电容0~100 nF的条件下,输出稳定无自激振荡;在无外接电容的情况下,当负载在1μs内从0 mA到300 mA之间跳变时,下冲与上冲电压仅分别为67 mV和72.5 mV。

To meet the requirements of large current output and fast transient response in multi-load power supply applications and reduce the cost of peripheral component,a capacitor-less low dropout regulator(LDO)was designed with 300 mA current output capacity.The main pole position was moved to the inside of the regulator by using the main pole frequency compensation technology,which overcomes independence of its frequency stability of traditional LDO on the offchip capacitance.A dual-loop control structure was adopted in the voltage stabilizing loop.The high-gain main loop composed of four-stage amplifier ensures the accuracy of output voltage.The fast transient response loop composed of a high-speed common-gate amplifier achieves fast response to output voltage.The circuit was designed based on 5 V 0.35μm CMOS technology.Simulation and test results show that the output is stable without self-excited oscillation when the load current is 0-300 mA and the output capacitance is 0-100 nF.In the absence of external capacitor,when the load jumps from 0 mA to 300 mA within 1μs,the overshoots and undershoots are less than 67 mV and 72.5 mV respectively.