用于微波倍频链的低噪声电压源

论文总字数：26959字

摘 要

低噪声LDO在噪声敏感电路如锁相环、倍频器、射频信号电路、高速数模混合电路等的电源管理中起着十分重要的作用。本文调研分析了国内外低噪声LDO的研究现状，提出了一款应用于微波倍频链的基于传统LDO结构的稳压源。分析和对比开关稳压器与低压差线性稳压器的特点得出LDO具有更简单的结构、更低的噪声，在低噪声应用领域有着天然的优势。简单分析了传统LDO结构各部分的作用以及原理，比较了用不同类型晶体管作为调整管时LDO具有的特点，为了满足本文设计中低噪声和可带大负载的要求，采用了BC550C作为调整管。对LDO中噪声源的分析奠定了本文LDO设计的基础。为了满足低噪声的要求，本文设计中采用两只白光LED产生参考电压，并采取了预调整加低通滤波的结构，采用ADI公司生产的低噪声运算放大器AD797AR作为误差放大器和比例放大器，采用低噪声硅功率管BC550C作为调整管。为了满足可输出大负载电流的要求，采用了10只BC550C并联的方式，并在每只管子的发射级都串联了1Ω电阻，保证了电流较为均匀地分配。设计了LDO的PCB板并且测试，结果表明输出电压为9.91V、输出电流750mA，10Hz到10KHz范围内噪声为1.20μVrms; 输出电压为11.90V、输出电流750mA，10Hz到10KHz范围内噪声为1.02μVrms。忽略电源噪声的影响，输出噪声低于1μVrms。

关键词 ：低压差线性调整器，白光LED，低噪声，NPN

Abstract

Low noise LDOs are widely used in the power supply regulation of noise-sensitive circuits, such as PLL, frequency multiplier, and high speed mixed-signal circuits. The researches into Low noise LDOs now home and abroad are investigated and summarized firstly, and then a conventional LDO structure is proposed, which is used in microwave frequency multiplier chain. The analysis and comparison between switching regulators and LDOs reveals that LDOs have greater advantages in the low noise area. The principle of a conventional LDO and the roles of its components are briefly described. BC550C is used as pass-transistor in the proposed structure in order to reach the low noise target based on the characteristics of LDOs using different transistors as pass-transistor. The analysis of noise sources in the LDO is the fundamentals of the proposed LDO in the paper. In order to reach the low noise goal, two white light LED are used to generate voltage reference, pre-regulation and low pass filtering structure is applied, and AD797AR of ADI is used as proportional amplifier and error amplifier, and also low noise Si small power transistors BC550C are used as pass-transistors. Ten BC550Cs are used for large output current, and each transistor’s emitter has a 1Ω series resistor for dividing output current near equally among these pass-transistors. The proposed LDO is realized on a PCB, and the measurements show that the integrated noise in 10Hz-10KHz is 1.20 μV rms with output voltage 9.91V and output current 750mA, and 1.02 μV rms with output voltage 11.90V and output current 750mA. If the noise of power supply is ignored, the output integrated noise of the proposed LDO is lower than 1μV rms.

KEY WORDS:LDO, white light LED, low noise, NPN

目 录

摘要 …………………………………………………………………………………………………Ⅰ

Abstract ………………………………………………………………………………………… Ⅱ

1. 绪论………………………………………………………………………………………1
   1. 项目背景与研究意义………………………… ……………………………………1
   2. 国内外研究现状……………………………………………………………………2
      1. 国外低噪声LDO研究现状……………………………………………2
      2. 国内低噪声LDO研究现状……………………………………………3
   3. 本文工作及内容安排………………………………………………………………4
   4. 本章小结………………………………………………………………………………5
2. LDO结构及原理分析…………………………………………………………………6

2.1 LDO的基本结构和电压调整原理…………………………………………………6

2.2 LDO的性能指标…………………………………………………………………8

2.3 本文LDO设计指标…………………………………………………………………9

2.4 本章小结…………………………………………………………………………………9

第三章 LDO中的噪声源以及常用噪声抑制技术…………………………………………10

3.1 电子系统中的噪声…………………………………………………………11

3.2 LDO中的噪声源……………………………………………………………12

3.3 LDO中常用噪声抑制技术…………………………………………………13

3.4 本章小结………………………………………………………………………………15

第四章 本文提出的LDO结构…………………………………………………………16

4.1 本文设计指标………………………………………………………………16

4.2 本文提出的LDO结构……………………………………………………16

4.2.1 参考电压的设计……………………………………………………17

4.2.2 电压预调整和低通滤波……………………………………………18

4.2.3 误差放大器和调整管………………………………………………18

4.2.4 系统稳定性分析……………………………………………………21

4.2.5 系统功率抑制比分析………………………………………………22

4.2 本章小结………………………………………………………………………………24

第五章 实验测试…………………………………………………………………………25

5.1 测试准备……………………………………………………………………25

5.2 LDO 噪声测量………………………………………………………………27

5.3 本章小结………………………………………………………………………………33

第六章 总结………………………………………………………………………………34

参考文献……………………………………………………………………………………35

致谢…………………………………………………………………………………………37

剩余内容已隐藏，请支付后下载全文，论文总字数：26959字