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A Guide to Using JFETs for Voltage Controlled Circuits


Linear Integrated Systems manufactures a variety of FETs (Field Effect Transistors). In particular they have a variety of matched dual products. There are advantages in having matched devices. For example, if you are building a twochannel stereo audio product, having two or four devices in the same package allows for the two audio channels to be more closely matched. This paper will explore using FETs in voltage controlled circuits. Several approaches will be shown: 

  1. 1. Using FETs as voltage controlled resistors. 

  2. 2. Using FETs as voltage controlled amplifiers and active mixers. 

  3. 3. Using FETs as voltage controlled phase shifters for processing music. 

  4. 4. Using FETs as voltage controlled band pass filters. 

We will also explore ways to reduce nonlinearities or distortions and automatically bias the FETs.

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