摘要
以设计输出电流为800mA的高稳定线性稳压器(low-dropout voltage regulator,LDO)为目标,利用工作在线性区的MOS管具有压控电阻特性,构造零点跟踪电路以抵消随输出电流变化的极点,并且采用了改进型米勒补偿方案使电路系统具有60°的相位裕度,达到了大输出电流下的高稳定性要求.另外,分析了电路在转换发生时电路结构参数和负载整流特性的关系,提出了一种能在瞬间提供大电流的转换速率加强电路,达到了在负载电流从800mA到10mA跳变时,输出电压的跳变量控制在60mV以内,并且最长输出电压恢复时间在500μs以内.芯片采用CSMC公司的0.6μm CMOS数模混合信号工艺设计,并经过流片和测试,测试结果验证了设计方案.
A design of a low-dropout （LDO） voltage regulator with an output current of 800mA is proposed. By introducing a zero-pole tracking circuit with a MOS resistor working in the linear region, the frequency response is independent of the load current. Moreover,with ameliorated miller compensation,a 60° phase margin is guaranteed. Based on the analysis of slewing behavior versus circuit parameters,the load regulation property is improved with a slew rate enhancement circuit which can supply a large current to speed up the slew rate. The precision of the output voltage is maintained within ± 60mV under varying load conditions from 800 to 10mA, and the settling time is about 500μs. The chip is implemented in CSMC 0.6#m mixedsignal technology. The designed circuit is validated by the results of the chip test.
关键词
低压差线形稳压器
稳定性
改进型米勒补偿
超调量控制
low dropout voltage linear regulator
stability
ameliorated miller compensation
overshoot control
