基于带隙基准源电路的噪声分析

Noise analysis based on band-gap reference circuit

噪声是制约电路特性的重要因素之一,提出通过优化电路降低噪声的方法,并在带隙基准源电路中实现。首先分析了电路噪声的主要来源,并针对带隙基准电路中不同元件的工作特点进行噪声源分析,根据该电路的系统结构推导出传递函数,进而得到电路噪声输出表达式。在综合考虑MOS器件热噪声和闪烁噪声对输出噪声的贡献后,根据具体表达式提出电路优化方法,对高精度模数转换器中带隙基准源电路的器件尺寸进行改进后,仿真结果表明,电路噪声减小了70%以上,噪声最大值仅为24,满足了高精度ADC电路的需要。

Noise is one of key aspects for influencing circuit properties in modern circuit and system.A novel method based on circuit improvement is proposed to decrease the noise,which is demonstrated by using band-gap reference circuit.The noise sources in circuit are analyzed in first part of this paper.Analysis on noise source is made on every component in band-gap reference circuit.Some key equations of noise output are obtained subsequently based on transfer functions,which deduced on system block.The design method for improving noise in circuit level is proposed.The method is applied on the reference circuit in a high resolution analog to digital converter.Some alternations are made on the dimensions of MOS transistors in the circuit.The simulation result shows that the noise is decreased above 70%.The maximum value is as small as 24 μv/Hz^（1/2）noise.