AN105 - Vishay Siliconix

AN105 FETS AS VOLTAGE-CONTROLLED RESISTORS

www.DataSheet4U.com AN105 FETs As VoltageĆControlled Resistors Introduction: The Nature of VCRs A voltage-controlled resistor (VCR) may be defined as a three-terminal variable resistor where the resistance value between two of the terminals is controlled by a voltage potential applied to the third. For a junction field-effect transistor (JFET) under certai.

Features

and is symbolized by VGS = VGS(off). Thus the device functions as a voltage- controlled resistor. Figure 1 details typical operating characteristics of an nchannel JFET. Most amplification or switching operations of FETs occur in the constant-current (saturated) region, shown as Region II. A close inspection of Region I (the unsaturated or pre-pinchoff area) reveals that the effective slope indicative of conductance across the channel from drain-to-source is different for each value of gate-source bias voltage. The slope is relatively constant over a range of applied drain voltages, so long as.