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在许多测量和控制系统中,希望获得几个摸拟信号的乘积,也希望有大量的摸拟乘法器。在反馈网路中应用场效应晶体管(FET)的乘法器提供了高的精度和宽的频率响应。反馈乘法将场效应晶体管(Q_1)放在运算放大器的反馈回路中,其电导率可以是门电压的线性函数(图1)。如果该门受放大器的输出 e_c 控制,则这一回路能用方程1a 表示。从方程1b 中我们可以发现,场效应管的电导是输入电压(V_1)的
In many measurement and control systems, it is desirable to obtain the product of several analog signals and also to have a large number of analog multipliers. Multipliers of field effect transistors (FETs) in the feedback network provide high accuracy and wide frequency response. Feedback multiplication places the field effect transistor (Q_1) in the feedback loop of the op amp whose conductivity can be a linear function of the gate voltage (Figure 1). If the gate is controlled by the amplifier output e_c, this circuit can be represented by Equation 1a. From Equation 1b we can see that the conductance of the FET is the input voltage (V_1)