一种快速响应无输出电容的LDO设计

发布时间：2018-05-05 01:06

本文选题：无输出电容 + 线性调整器　；参考：《电子科技大学》2016年硕士论文

【摘要】：随着医疗电子、传感器、物联网等电子行业的发展,芯片的集成度越来越高,为了将低压差线性调整器(LDO)集成在芯片内且省去传统LDO输出电压处的滤波电容,进而节省封装成本和外围元件成本,无输出电容型LDO结构以及相关电路设计技术被广泛研究。无输出电容型LDO没有大的输出滤波电容,进而使得负载在空载和满载之间切换时输出电压的响应时间慢,动态误差比较大;另外,这种结构的LDO主极点一般设计在EA输出端,这会使得空载时由于输出端的极点移动到低频而恶化环路稳定性。因此输出端具有最低电流限制,而过大的静态电流会使得LDO很难用于低功耗设备。为了设计一快速响应无输出电容型LDO,本文首先对LDO的基本工作原理和它的各项技术指标进行了分析,然后再对文献中出现的几种常见无输出电容型LDO以及它们的改进结构作了研究分析,其中包括阻尼系数控制结构、品质因数控制结构、倒置型跟随器结构和双调整管结构,这些结构有助于提高轻载时的稳定性以及加快瞬态响应速度。借鉴文献中的思想,本文设计了一种快速响应无输出电容的LDO,该设计基于SMIC-0.18μm-CMOS工艺,电路包括亚阈值基准模块、电流偏置模块和LDO主模块。其中LDO结构采用可自动重构的双调整管结构,其可以根据负载电流自动切换电路进入两级放大或者三级放大状态。其中误差放大器结构采用沟道长度分裂式结构以便引入Cascode Miller补偿。Spectre仿真结果表明,系统静态电流50μA,输出端允许最小电流10μA(包含分压电阻之路的电流),当负载在轻载(5μA)和满载(50mA)之间跳变时,输出电压的动态误差都小于100mV,且都在2μs内恢复稳定,在允许的输入电压范围和负载电流范围内的进行瞬态仿真,结果显示该LDO都可以稳定工作。
[Abstract]:With the development of medical electronics, sensors, Internet of things and other electronic industries, the integration of chips is becoming more and more high. In order to integrate the low voltage difference linear regulator (LDO) into the chip and eliminate the filter capacitance at the traditional LDO output voltage, Thus, the cost of packaging and peripheral components can be saved, and the output capacitive LDO structure and related circuit design techniques have been widely studied. The output capacitor type LDO has no large output filter capacitance, which makes the response time of output voltage slow and the dynamic error larger when the load switches between no-load and full load. In addition, the main pole of LDO is generally designed at the output end of EA. This will make the loop stability worse when the output pole moves to low frequency. Therefore, the output has the lowest current limit, and the excessive static current makes it difficult for LDO to be used in low power devices. In order to design a fast response output capacitive LDO, this paper first analyzes the basic working principle of LDO and its technical specifications. Then, several kinds of common output capacitive LDO and their improved structures are studied and analyzed, including damping coefficient control structure, quality factor control structure, inverted follower structure and double adjusting tube structure. These structures help to improve the stability of light load and speed up the transient response. Based on SMIC-0.18 渭 m-CMOS technology, this paper designs a fast response without output capacitance. The circuit includes sub-threshold reference module, current bias module and LDO main module. The structure of LDO adopts double adjusting tube structure which can be automatically reconfigurable. It can automatically switch the circuit into two stage amplifier or three stage amplifier state according to the load current. The error amplifier structure adopts channel length split structure to introduce Cascode Miller compensation. The simulation results show that, The static current of the system is 50 渭 A, and the output terminal allows a minimum current of 10 渭 A (the current with the path of partial resistance, when the load jumps between light load and full load of 50 Ma), the dynamic error of the output voltage is less than 100 MV, and the output voltage is stable within 2 渭 s. The transient simulation results within the allowable input voltage range and load current range show that the LDO can work stably.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM44

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