基于动态零点补偿的低压降线性稳压芯片的研究与设计

【作者】 王进军；

【导师】 田泽；

【作者基本信息】 西北大学 ， 微电子学与固体电子学， 2007， 硕士

【摘要】 本论文在分析一般负反馈系统稳定性的基础上，对LDO线性稳压器（Low Dropout Linear Regulator）的稳定性进行了深入地分析研究和稳定性动态零点补偿设计。首先，建立了LDO线性稳压器系统的交流小信号等效模型，在此等效模型的基础上，采用频域傅立叶分析的方法，求出了LDO线性稳压器系统的闭环传输函数，在对系统零极点分析的过程中发现，LDO线性稳压器系统的主极点的位置随负载电流的大小在变化：f_po=λI_L／2πC_out，负载电流大小的不同使得LDO线性稳压器随时都可能振荡。针对此情况，本论文给出了一种LDO线性稳压器稳定性动态零点补偿的方法，该方法的主要思想是利用MOS管开关电阻和寄生电容构成零点补偿网络，通过负载采样电流动态调整MOS管的工作状态，进而调节补偿电阻电容的值，使其产生的动态补偿零点抵消LDO线性稳压器系统主极点位置随负载电流大小变化给LDO线性稳压器稳定性带来的影响，从而使得LDO线性稳压器系统的稳定性与负载电流大小无关。之后，本论文利用上述给出的动态零点补偿方法，采用UMC 0.6um BiCMOS process进行了一款应用于各类无线通讯设备高性能、高稳定LDO线性稳压芯片设计。最后，对所设计的LDO线性稳压芯片进行了稳定性验证和性能参数仿真，仿真结果表明：负载电流从0变化到150mA时，该LDO线性稳压芯片闭环传输函数曲线变化很小，具有很高的稳定性；其典型参数仿真结果如下：输出电压2.5V±0.15％；最大漏失电压65mV；最大正常工作输出电流150mA；最大静态电流163uA；短路电流620mA；最大启动时间200us；线性调整率0.02％／V；负载调整率0.0008％／mA；电源抑制比75dB（低频）；输出噪声密度0.9uV／（Hz）^1／2；AC线性调整率：0.73mV_p-p，热关断温度160℃；欠压关断电压2.43V。更多还原

【Abstract】 Based on analyzing the stability of a normal negative feed-back system, this paper studied the stability of LDO （Low Dropout Linear Regulator） deeply and made a design with stability dynamic zero compensation.Firstly, modeled the AC small signal equivalent models of LDO, based on this model, using the method of Fouries analysis in frequency domain, evaluated the closed transmit function of LDO. During analyzing the pole- zero point of the system, we found that the position of the main pole-point (f_po=λI_L/2πC_out)of LDO will be changed when the load current changed, the changing of load current will made LDO oscillate any time. Aimed to this situation, this paper gived out a dynamic zero compensation method of LDO’s stability, the main idea of this method is employing switch resistor and parasitical capacitor of MOSFET to constitute dynamic zero compensation network, applying sampled current of load current to regulate the state of MOSFET to change the value of these resistors and capacitors, so the dynamic compensation zero-point produced by the dynamic zero compensation network eliminates the influence to LDO’s stability, which produced by the change of the load current value, so the stability of LDO is irrelevant to the value of the load current.After that, this paper using the compensation method above on designed a high-performance and high-stability LDO chip based on UMC 0.6um BiCMOS process, which can be used to all kinds of wireless communication equipments.At last, this paper tested the stability and simulated the performance parameter of the design, the simulation results indicated that under the situation of different load current from 0 to 150mA, the curves of the closed transmit function of the chip changed slightly, so this chip has higher stability; the results of the performance parameter simulated as follows: the output voltage is 2.5V±0.15％; the maximum dropout voltage is 65mV; the maximum working output current is 150mA; the maximum quiescent current is 163uA; the maximum short circuit current is 620mA; the maximum response time is 200us; the lining regulation error is 0.02％/V; the load regulation error is 0.0008％/mA; the output noise density is 0.9uV/（Hz）^1/2; the PSRR is 75dB at low frequency segment; AC lining regulation is 0.73mV_P-P; the temperature of thermal shutdown is 160℃; the voltage of under voltage lockout is 2.43V.更多还原