基于动态频率补偿的LDO电路设计

文中提出了一种基于动态频率补偿技术的LDO电路。通过添加电压缓冲器,提高了LDO的环路增益和瞬态响应特性。该电路通过电流镜采样调整管电流,使主极点频率与第三极点频率随负载电流的改变而产生相同倍数的变化,克服了LDO零极点随负载变化而导致环路稳定性变差的问题。文中设计采用中电二十四所HC12.BJT工艺,利用Spectre仿真工具进行仿真,研究了不同负载电流下该LDO的频率特性及其稳定性问题。仿真结果表明,该电路在10 μA~100 mA负载电流的变化范围内,LDO环路的相位裕度保持在50°~70°之间,证明提出的LDO调整器具有良好的稳定性。

Design of LDO Circuit Based on DynamicFrequency Compensation

This paper presented a LDO circuit based on dynamic frequency compensation. The LDO loop gain and transient-response characteristics were improved by adding a voltage buffer. The circuit used a current mirror to sample the current of pass transistor, making the frequency of the main pole and the third pole present the same change with the load current. With this method, the problem of loop stability caused by LDO’s zeros and poles changing with load current was overcome. Based on CETC 24 ^th Institute’s HC12 BJT technology and simulation conducted by Spectre, the LDO’s frequency characteristic under different load current was studied. The simulation results demonstrated that the LDO loop had a phase margin of 50° to 70° when load current varied from 10 μA to 100 mA, proving the good stability of the proposed LDO regulator.