Voltage Controlled Resistor Mosfet

The jfet and the mosfet.

Voltage controlled resistor mosfet. To prevent the resistance from ever going too low you could put a low valve high power resistor in series. The gate electrode is electrically insulated from the main semiconductor by a thin layer of insulating material glass seriously. Most commonly the resistance rds from drain to source is modulated by the gate voltage vgs. Vcrs are most often built with field effect transistors fets.

Two types of fets are often used. The resistor will only produce 4v drop if the current through the resistor will 400ma 4a. The ohms law is applied in this scenario. The output of the op amp turn on and control the mosfet until the voltage drop across the shunt resistor became 4v.

The field effect transistor as a voltage controlled resistor we consider the use of a n channel fet as a voltage controlled resistor where the resistance between the drain and source is controlled by the gate source voltage. It won t be very easy to tune it to behave like a proper resistor. There are two distinct regions. In the ohmic region1 the drain to source current i.

These resistors in turn may be used as the control element in more complicated electronic circuits. The mosfet is a three terminal device. A voltage controlled resistor vcr is a three terminal active device with one input port and two output ports. Basic voltage controlled resistor vcr circuits one of the simplest uses of a voltage controlled resistor is an electronically controlled attenuator or volume control.

In the ohmic region which is quite narrow in terms of output voltage the linearity is poor and it also depends on input voltage. Technically the mosfet can operate as a variable resistor but there are two main issues. Mosfet is a voltage controlled field effect transistor that differs from a jfet. The answer is yes e g vcr11 but it turns out that virtually any other fet e g jfet and mosfet can be used as a voltage controlled resistor.

In the source supply and apply the control voltage between the power supply side of the resistor and the gate this will stabilise the current through the mosfet to some extent. The basic idea behind using the mosfet as voltage controlled resistor is to control the width of the conducting channel resistance between two terminals by modulating the voltage at the third terminal. This is because voltage current x resistance.