负反馈对放大电路三阶互调的影响  

Effect of negative feedback on third-order intermodulation of amplifier

作　　者：龚淑君[1] 陈邦媛[1] 

机构地区：[1]浙江大学信息与电子工程学系,浙江杭州310027

出　　处：《浙江大学学报（工学版）》2004年第8期961-965,共5页Journal of Zhejiang University：Engineering Science

摘　　要：为了说明负反馈对放大电路线性的具体改善程度,以放大电路的三阶互调为分析对象,推导出带负反馈放大网络的三阶互调失真幅度比和三阶截点输入信号幅度的一般公式.将一般公式应用于金属氧化物半导体(MOS)场效应管差分放大电路,分析在源极引入电阻负反馈后电路三阶截点输入信号幅度的变化.与不加负反馈时电路的此项指标相比,可得负反馈对电路线性改善的定量关系.电路的仿真结果表明,对电阻负反馈电路的理论分析适用于电感负反馈电路;随着负反馈电阻或电感值的增加,电路的线性进一步得到改善,但增益下降.在采用负反馈改善电路线性时要考虑它对增益的影响。In order to get information on the linearity improvement of amplifier circuit by using negative feedback, its general expressions of third-order intermodulation were deduced, which involved the intermodulation distortion and the input third intercept point. The general expressions were used in the analysis of MOSFET (metal oxide semiconductor field effect transistor) differential amplifier. The input third intercept point of the circuit after using source resistive degeneration was analyzed. The quantitative relationship between the negative feedback and its linearity improvement was obtained. The simulation results show that the analytical result is valid for the amplifier circuit with inductive degeneration; and the linearity of circuit is improved with the increment of feedback resistance or inductance. When using negative feedback to improve the linearity of circuit, its effect on the gain of circuit should be considered.

关 键 词：负反馈 三阶互调失真 输入三阶截点 差分放大电路 

分 类 号：TN722[电子电信—电路与系统]