answersLogoWhite

0

Transfer Characteristic of JFETThe transfer characteristic for a JFET can be determined experimentally, keeping drain-source voltage, VDSconstant and determining drain current, ID for various values of gate-source voltage, VGS. The circuit diagram is shown in fig. 9.7 (a). The curve is plotted between gate-source voltage, VGS and drain current, ID, as illustrated in fig. 9.8. It is similar to the transconductance characteristic of a vacuum tube or a transistor. It is observed that

(i) Drain current decreases with the increase in negative gate-source bias

(ii) Drain current, ID = IDSS when VGS = 0

(iii)Drain current, ID = 0 when VGS = VD The transfer characteristic follows equation (9.1)

The transfer characteristic can also be derived from the drain characteristic by noting values of drain current, ID corresponding to various values of gate-source voltage, VGS for a constant drain-source voltage and plotting them.

It may be noted that a P-channel JFET operates in the same way and have the similar characteristics as an N-channel JFET except that channel carriers are holes instead of electrons and the polarities of VGS and VDSare reversed.

User Avatar

Wiki User

13y ago

What else can I help you with?

Continue Learning about Physics

Why emitter bias circuit is called self bias?

The emitter bias circuit is called self-bias because the bias voltage across the emitter-resistor is based on the transistor's own characteristics. The bias voltage adjusts itself based on the varying collector current to stabilize the operating point of the transistor. It is a self-adjusting mechanism that helps maintain a stable bias point for the transistor.


What are the factors causing Bias instability?

Causes of Bias instability include temperature and current gain. High temperature will change the parameters in the transistor. When manufacturing transistors there is a possibility of them having different parameters.


What is JFET and VVR?

JFET as a VVR-Voltage Variable ResistorFET is a device that is usually operated in the constant-current portion of its output characteristics. But if it is operated on the region prior to pinch-off (that iswhere VDS is small, say below 100 mV[ohmic region of JFET]), it will behave as a voltage-variable resistor (WE). It is due to the fact that in this region drain-to-source resistance RDS can be controlled by varying the bias voltage VGS. In such applications the FET is also referred to as a voltage-variable resistor or volatage dependent resistor. It finds applications in many areas where this property is useful.Figure shows the drain characteristic curves for a 2N 5951 in the ohmic region (i.e. for low VDS). From the characteristic curve it can be seen that RDS varies with VGS. For example, when VGS = 0, RDS = 133 ohm and when VGS = - 2 V, RDS = 250 ohm. Because of this a JFET operating in the ohmic region with small ac signals acts as a voltage-controlled resistance.Note that the drain curves shown in figure,extend on both sides of the origin. This means that a JFET can be employed as a voltage-variable resistorfor small ac signals, typically those less than 100 mV. When it is employed in this way, it does not require a dc drain voltage from the supply. All that is required is an ac input signal.


What is the Effect of temperature on reverse biase of led?

As temperature increases, the reverse bias voltage of an LED also increases. This is due to the temperature-dependent nature of the semiconductor material used in the LED, which affects the bandgap energy and subsequently the reverse bias characteristics. It is important to consider and compensate for these temperature effects when designing LED circuits for reliable performance.


What is it called when you want the results of your experiment to come out a certain way?

When someone wants the results of an experiment to come out a certain way, it is called experimenter bias or confirmation bias. This can lead to skewed results and undermine the validity of the experiment.

Related Questions

In a JFET gates are always?

forward bias


The primary control on drain current in a JFET is exerted by?

Gate reverse bias


Why you bias in jfet transistor in nano ampere?

A: A FET has a very hi impedance it requires mostly potential as opposed to current like a transistor does,


Why should a JFET be operated with only reverse bias on the gate source?

What is the venin and norton equivalent circuit comment?Read more: What_is_the_venin_and_norton_equivalent_circuit_comment


What are the characteristics of forward bias?

characteristics of forward biased


Why must the gate to source voltage of an n channel Jfet always be zero or negative?

to made reverse bias junction between gate to source


Why should a JFET be operated with only reverse bias on the gate?

If the gate-channel junction of a JFET was not reverse biased the JFET would just act as a forward biased diode across that junction and the gate would cease to have any control over the channel conductance. For the same reason in a MOSFET the substrate-source/channel/drain junction must remain reverse biased. The MOSFET could not act as a MOSFET.


What does gm0 represent in a BJT amplifier circuit?

gm0 is not used in BJT amplifier circuits; it is used in JFET circuits. It is the transconductance at zero gate bias. Since the transconductance varies as the bias is varied, this gives a benchmark level at a given defined point, and other transconductances can be calculated from it as a function of the amount of negative bias on the gate. If it were linear it would be the same everywhere, but it is not.


What are the characteristics of fixed bias?

It is a bias of a fixed voltage supplied by a separate low-power bias supply. Early radios used a 9 v tapped bias battery. In some amplifiers fixed bias can be dispensed with and the bias voltage is derived from one of the currents in the circuit.


Characteristics of curve of an ideal diode with diagram?

0V forward bias knee voltage0 ohm forward bias resistance0A reverse bias currentinfinite ohm reverse bias resistanceno parasitic capacitance or inductance


Why fet operated in reverse bias?

you want to keep the channel electrically isolated from the gate (jfet) or substrate (mosfet) so that it operates as a fet, don't you? if it was forward biased it would just be a diode with no field effect.


What does self - enhancing bias mean?

Self-enhancing bias refers to the tendency for individuals to attribute their successes to internal factors such as their abilities or efforts, while attributing their failures to external factors such as luck or situational circumstances. This bias can lead to overestimating one's capabilities and achievements while underestimating the influence of external factors on outcomes.