Voltage controlled attenuators using field effect transistors

A FET operated so that channel pinch-off is avoided behaves like a voltage controlled variable resistor. This paper considers a "voltage divider" attenuator using the device in this way. Attenuation (in decibels) varies almost linearly with control voltage over a range. Distortion may be less than 0.01 percent, temperature effects are usually negligible, and the network can operate satisfactorily up to a few megahertz. Circuits of this kind demand a FET having special characteristics.