结型场效应管可以用作宽范围的电压控制电阻,但存在着非线性问题。CX-75A型双侧向井下仪器用文氏振荡器产生主电流。若在文氏振荡器中用结型场效应管作运算放大器的自动增益控制,则它的非线性会带来振荡信号的失真。对振荡信号失真度的要求和对振荡器的温度稳定性的要求是相互矛盾的。可以用反馈技术使场效应管线性化,并控制振荡信号的失真度。实验证明,这种方法是有效的。 Junction FET can be used as a wide range of voltage control resistors, but there is a non-linear problem. The CX-75A dual lateral downhole instrument generates the main current using a Wenger oscillator. If the Wenger oscillator with a junction FET for the automatic gain control amplifier, it will bring the non-linear oscillation signal distortion. The requirements of the oscillation signal distortion and the temperature stability of the oscillator are mutually contradictory. You can use feedback technology to linearize the FET, and control the degree of distortion of the oscillation signal. Experiments show that this method is effective.