like and respect yourself. Thought of the Day The way you give your name to others is a measure of how much you like and respect yourself. गुरुवार, 2 मई 2019 FETs

Field Effect Transistors (FETs) D.C. Kulshreshtha गुरुवार, 2 मई 2019 FETs

Types of FETs Two main types : Junction Field Effect Transistor (JFET). Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET). (also called IGFET) गुरुवार, 2 मई 2019 FETs

Both are fabricated as discrete components and as components on IC. MOS transistors can be made very small. Digital logic memory can be implemented exclusively by using MOSFETs (without resistors and diodes). VLSI circuits are made using MOS technology. गुरुवार, 2 मई 2019 FETs

Two types of MOSFETs Depletion-type MOSFET (DE MOSFET). (Similar to JFET). Enhancement-type MOSFET (EN MOSFET). गुरुवार, 2 मई 2019 FETs

FETs Two types: These are unipolar transistors. N-type channel. P-type channel. These are unipolar transistors. गुरुवार, 2 मई 2019 FETs

JFET गुरुवार, 2 मई 2019 FETs

Analogy between BJT & JFET गुरुवार, 2 मई 2019 FETs

Formation of Channel गुरुवार, 2 मई 2019 FETs

Working of JFET गुरुवार, 2 मई 2019 FETs

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This is called pinch-off voltage, VP. At point P, the two depletion regions tend to meet at a point near drain. This is called pinch-off voltage, VP. The channel width can reduce only to a constant minimum value. Increasing vDS beyond VP extends the length of the constricted channel. The channel acts as a current limiter. Saturation Current, IDSS –the Drain-to- Source current with the gate Shorted. गुरुवार, 2 मई 2019 FETs

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JFET Characteristics गुरुवार, 2 मई 2019 FETs

Drain Characteristics of N-Channel JFET गुरुवार, 2 मई 2019 FETs

As a convention, Vp is negative voltage for N-channel JFET. The minimum value of gate-to-source voltage required to make the drain current zero is called gate-to-source cut-off voltage, VGS(0). As a convention, Vp is negative voltage for N-channel JFET. When VGS = Vp, the current ID reduces to zero. The curve joining the pinch-off points is a parabola, given by गुरुवार, 2 मई 2019 FETs

The saturation voltage VDS(Sat) on the curve is given as गुरुवार, 2 मई 2019 FETs

In the ohmic region, or voltage controlled resistance region, or the triode region, the resistance is controlled by VGS. The JFET is normally operated in the active region, or pinch-off region, or saturation region. In this region, the JFET gives linear amplification. गुरुवार, 2 मई 2019 FETs

JFET Transfer Characteristics गुरुवार, 2 मई 2019 FETs

Note that the curve meets the iD-axis at IDSS and VGS-axis at –Vp. The curve is given by Shockley Equation. गुरुवार, 2 मई 2019 FETs

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MOSFETs Reading Assignment : From Page 163 to 173

FET Parameters Dynamic Drain Resistance (rd) : Typically, it is about 500 kΩ.

Trans-conductance or Mutual Conductance (gm) : Typically, it ranges from 150 μS to 400 μS.

(3) Amplification Factor (μ) : Typically, it is about 150.

Relationship between parameters

Review Types of FETs. JFET. Analogy between BJT & JFET. Formation of Channel. JFET Characteristics. Drain Characteristics of N-Channel JFET. Shockley Equation. गुरुवार, 2 मई 2019 FETs