JFET biasing

Two biasing arrangements for an N-channel JFET are shown in Fig. 1. These hookups are similar to the way an NPN bipolar transistor is connected, except that the source-gate (SG) junction is not forward-biased.
At A, the gate is grounded through resistor R2. The source resistor, R1, limits the current through the JFET. The drain current, I_D, flows through R3, producing a voltage across this resistor. The ac output signal passes through C2.
At B, the gate is connected to a voltage that is negative with respect to ground through potentiometer R2. Adjusting this potentiometer results in a variable negative E_G between R2 and R3. Resistor R1 limits the current through the JFET. The drain current, ID, flows through R4, producing a voltage across it; the ac output signal passes through C2.
In both of these circuits, the drain is positive relative to ground. For a P-channel JFET, reverse the polarities in Fig. 1. The connections are somewhat similar to the way a PNP bipolar transistor is used, except the SG junction isn’t forward-biased.

Fig. 1: Two methods of biasing an N-channel JFET. At A, fixed gate bias; at B, variable gate bias.

Typical JFET power-supply voltages are comparable to those with bipolar transistors. The voltage between the source and drain, abbreviated ED, can range from about 3 V to 150 V; most often it is 6 V to 12 V.
The biasing arrangement in Fig. 1A is commonly used for weak-signal amplifiers, low-level amplifiers and oscillators. The scheme at B is more often employed in power amplifiers having a substantial input signal.

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الحساسات النانوية لرصد وتعقب حرائق الغابات

التكامل بين تكنولوجيا النانو وتكنولوجيا الاستشعار من بعد لرصد تلوث الهواء الجوي

الحساسات النانوية للحالة الصلبة

الحساسات النانوية لرصد ملوثات الهواء

تكنولوجيا النانو وصناعة الحساسات

الحساسات النانوية

تقنية النانو في الطباعة على الأسطح Nano–Lithography

تقنية الطباعة على الأسطح Lithography

التنافس العالمي في إنتاج الحاسبات المعتمدة على تكنولوجيا النانو

قانون مور

تركيب الترانزستور وكيفية عمله

ماهية الترانزستورات