李洪品,杨发顺,马奎.基于偏流补偿的低失调运算放大器的设计[J]. 微电子学与计算机,2024,41(5):140-146. doi: 10.19304/J.ISSN1000-7180.2023.0314
引用本文: 李洪品,杨发顺,马奎.基于偏流补偿的低失调运算放大器的设计[J]. 微电子学与计算机,2024,41(5):140-146. doi: 10.19304/J.ISSN1000-7180.2023.0314
LI H P,YANG F S,MA K. Design of a low offset operational amplifier based on bias current compensation[J]. Microelectronics & Computer,2024,41(5):140-146. doi: 10.19304/J.ISSN1000-7180.2023.0314
Citation: LI H P,YANG F S,MA K. Design of a low offset operational amplifier based on bias current compensation[J]. Microelectronics & Computer,2024,41(5):140-146. doi: 10.19304/J.ISSN1000-7180.2023.0314

基于偏流补偿的低失调运算放大器的设计

Design of a low offset operational amplifier based on bias current compensation

  • 摘要: 基于双极型工艺,设计了一种具有低输入失调电压、低输入偏置电流的运算放大器。电路结构包含偏置电路、差分输入级电路、中间级电路和输出级电路。差分输入级电路采用共射-共基耦合对,能够降低失调电压,并且采用基极电流补偿结构抵消输入偏置电流在外围电路上所产生的影响,提高电路精度。中间级为整个电路提供增益,并且将双端输入信号转换为单端输出信号。输出级电路为AB类输出级,具有低静态功耗,能够提高电路效率,增大电路带负载能力并为负载提供更多功率。电路采用齐纳修调技术,在封装后对芯片进行修调,避免封装后引入的二次失调。流片后测试结果表明:在±15 V电源电压条件下,输入失调电压≤10 μV,输入偏置电流≤3 nA,输入失调电流≤1.5 nA,大信号电压增益≥ 110 dB。

     

    Abstract: An operational amplifier is designed based on bipolar process with low input offset voltage and low input bias current, which includes bias circuit, differential input circuit, intermediate circuit and output circuit. The differential input stage adopting cascode differential pairs can decrease offset voltage. Meanwhile, the base current compensation structure included in differential input stage can neutralize the influence of input bias current on peripheral circuitry and can increase circuit’s accuracy. The intermediate stage provides gain for the overall circuit and converts differential input signal to an output signal that is referenced to ground. The output stage, as Class AB structure that consumes low static power, improves circuit’s efficiency, boosts loading capability and provides more power for load. The circuit adopting Zena trimming can trim the chip after packaging, which can avoid second offset introduced after packaging. After taping out, the test results show that input offset voltage of less than 10 μV, input bias current of less than 3 nA, input offset current of less than 1.5 nA, large signal voltage gain of more than 110 dB at ±15 V power supplies.

     

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