柴吴尽 CMOS基准电流源

CMOS基准电流源设计

摘要

基准源是在电路系统中为其它功能模块提供高精度的电压基准，或由其转化为高精度电流基准，为其它功能模块提供精确、稳定的偏置的电路。它是模拟集成电路和混合集成电路中非常重要的模块。基准源输出的基准信号稳定，与电源电压、温度以及工艺的变化无关。

带隙基准源是集成电路中的重要单元，输出不随温度、电源电压变化的基准电压或电流。简单介绍了CMOS带隙基准源的基本工作原理；指出了限制其性能的主要因素；分析了低电源电压、低功耗、高精度和高PSRR四种类型的CMOS带隙基准源。

一款是应用于DAC的带隙基准电路。该基准电路的核心采用了PNP 晶体管串联来减小运放失调，运放采用的是具有高输入摆幅的折叠式共源共栅结构，偏置电路采用了低压共源共栅电流镜和自偏置低压共源共栅电流镜等结构来为整个基准电路提供偏置。本文基于SMIC 0.35μm工艺模型库，采用Hspice仿真工具对该基准电路进行仿真，仿真结果为：温度扫描从-40℃到100℃ ,基准源的温度系数为15.7ppm/℃；电源抑制比在1kHz时为75dB, 10kHz时仍有58dB。仿真结果表明，该基准电路完全能在DAC 系统中正常工作。

关键词CMOS基准电流源；低功耗；温度系数

Research of CMOS Bangap Reference Source

Abstract

A voltage reference source provides high-precision voltage reference for other functional modules in the circuit system, or high-precision current reference can transformed from it. It is a very important module in the analog integrated circuits and mixed-signal integrated circuits design. The output signal of the voltage reference is stable,and it is independent of supply voltage, temperature and process.

Bandgap reference source is an important unit in integrated circuits, which supplied reference voltage or current independent of temperature and supply voltage. The principle of CMOS bandgap reference source was described, and the design challenge was pointed out. Finally, CMOS bandgap reference sources with low supply voltage, low power, high precision and high PSRR were analyzed, respectively.

The bandgap reference is used in the DAC. The core of the reference circuit used PNP transistors in series to reduce amplifier offset, and the amplifier used the folded cascode structure to get high input swing, and the bias circuit used the low-voltage cascode current mirror structure and the self-biased low-voltage cascode current mirror structure to bias the entire reference circuit. In the thesis, we simulated the reference circuit by using the Hspice simulation tool based on the SMIC 0.35μm process. The simulation results are that the temperature coefficient of the references is 15.7 ppm/℃when temperature scaned from -40℃to 100℃,and the power supply rejection ratio is 75 dB at 1kHz and there is still 58 dB at 10 kHz. The simulation results showed that the reference

circuit can work normally in the DAC system.

Keywords CMOS current reference; Low power; Temperature coefficient

目录

摘要...................................................................................................................... I Abstract ............................................................................................................... II

第1章绪论 (6)

1.1 基准的几种主要类型 (6)

1.2 本文的研究背景和选题意义 (7)

1.3 主要研究内容 (8)

1.4 本章小结 (8)

第2章CMOS带隙基准源研究现状 (9)

2.1 CMOS带隙基准源基本原理 (9)

2.2 改进的CMOS带隙基准源 (11)

2.2.1 低电源电压CMOS带隙基准源电路 (11)

2.2.2 低功耗带隙基准源电路 (16)

2.2.3 高精度带隙基准源 (18)

2.3 本章小结 (21)

第3章两种典型CMOS基准电流源对比 (22)

3.1 一种低电压高精度CMOS基准电流源 (22)

3.1.1 电路描述 (23)

3.1.2 仿真结果 (25)

3.2 一种低温漂低电源电压调整率CMOS基准电流源 (26)

3.2.1 新型基准电流源理论与方案 (26)

3.2.2 仿真验证及结果分析 (31)

3.3 本章小结 (32)

第4章一种应用于DAC中的带隙基准源的设计 (34)

4.1 DAC模数转换器的原理 (34)

4.2 带隙基准电路设计指标 (37)

4.3 带隙基准电路设计 (37)

4.3.1 带隙基准主体电路设计 (37)

4.3.2 启动电路设计及基准稳定性考虑 (38)

4.3.3 运算放大器的设计 (40)

4.3.4 偏置电路设计 (42)

4.4 仿真结果 (44)

4.5 版图设计 (46)

4.5.1 设计规则 (46)