一种改进型低输入偏置电流的仪表放大器

曾惠礼; 肖筱; 尤路; 魏海龙

doi:10.19304/J.ISSN1000-7180.2021.1195

一种改进型低输入偏置电流的仪表放大器

doi: 10.19304/J.ISSN1000-7180.2021.1195

西安微电子技术研究所，陕西西安，710054

详细信息

作者简介:
曾惠礼男，(1994-)，硕士研究生.研究方向为高性能仪表放大器设计

肖筱女，(1987-)，硕士研究生，高级工程师.研究方向为模拟集成电路设计

尤路男，(1986-)，硕士研究生，高级工程师.研究方向为模拟集成电路设计

通讯作者:
魏海龙(通讯作者) 男，(1976-)，博士，研究员，硕士生导师.研究方向为模拟集成电路设计.E-mail: weihl007@126.com

中图分类号: TN431
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- 被引次数: 0
出版历程
- 收稿日期: 2021-10-24
- 修回日期: 2021-11-24
- 网络出版日期: 2022-11-29

An improved instrumentation amplifier with lowinput bias current

Xi′an Microelectronics Technology Institute, Xi′an 710054, China

摘要

摘要:
介绍了一种低输入偏置电流仪表放大器的设计.主要采用超β NPN输入器件并配合一种改进型的偏流自补偿结构，即通过在偏流补偿网络中使用一个横向PNP型器件替换PJFET器件的方法，以防止PJFET器件高温下栅漏电流对电路造成的影响，实现pA量级的极低输入偏置电流和pA/℃量级的偏流温漂系数.基于兼容金属薄膜电阻的40V单铝双极工艺，在保证低增益误差、低失调电压和高共模抑制比的同时，该电路具有较高的输入阻抗，适用于数据采集系统中对小信号的提取和放大.测试结果显示，改进后的仪表放大器常温下的输入偏置电流为0.69nA，输入失调电流为0.12nA，输入失调电压为21.54μV，增益G=100时的增益误差为0.05%，共模抑制比为119.41dB.
- 超β NPN器件 /
- 偏流自补偿 /
- 输入偏置电流 /
- 仪表放大器
Abstract:
This article discusses a low input bias current instrumentation amplifier, which mainly adopts ultra-β NPN input devices and cooperates with an improved bias current self-compensation structure, That is, by replacing the PJFET device with a lateral PNP device in the bias current compensation network, to prevent the gate leakage current of the PJFET device from affecting the circuit at high temperatures, and to realizes an extremely low input bias current of the order of pA and a bias current temperature drift coefficient of the order of pA/℃. Based on a 40V single aluminum bipolar process compatible with metal film resistors, this circuit has a high input impedancewhile ensuring low gain error, low offset voltage and high common mode rejection ratio, which is suitable for Small signal extraction and amplification in data collection systems.The test results show that the input bias current of the improved instrumentation amplifier at room temperature is 0.69nA, the input offset current is 0.12nA, and the input offset voltage is 21.54μV. When the gain G=100, the gain error is 0.05%, and the common mode rejection ratio is 119.41dB.
- Super β NPN device /
- Bias current self-compensation /
- Input bias current /
- Instrumentation amplifier

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图 1 仪表放大器电路原理图

Figure 1. Schematic diagram of instrumentation amplifier circuit

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图 2 输入缓冲放大器

Figure 2. Input Buffer Amplifier

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图 3 改进前的偏流补偿结构

Figure 3. Bias current compensation structure before improvement

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图 4 改进后的偏流补偿结构

Figure 4. The improved bias current compensation structure

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图 5 输入偏置电流温漂特性

Figure 5. Input bias current temperature drift characteristics

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图 6 输入偏置电流随电源电压的变化特性

Figure 6. Variation of input bias current with supply voltage

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图 7 输入偏置电流随共模电压的变化特性

Figure 7. Variation of input bias current with common mode voltage

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表 1 本文的IA与同类型产品参数对比

Table 1. Comparison of the parameters of IA in this paper and products of the same type

参数	本文		文献[12]
参数	仿真	实测	文献[12]
功耗/mA	3.80	3.90	0.90
输入偏置电流/nA	0.31	0.69	2.00
输入失调电流/nA	0.08	0.12	0.70
输入失调电压/μV	15.62	21.54	60.00
增益误差/%	0.02	0.05	0.20
共模抑制比/dB	133.60	119.41	118.00
转换速率/(V/μs)	5.40	5.10	1.20

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参考文献(12)

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