Category: Field Effect Transistors

Common Drain Amplifier Introduction In the common drain amplifier, the input signal is applied between the gate and drain and the amplified output voltage is developed across a resistor in the source-to-drain circuit. The drain is the terminal common to the input and the output sides. Figure 1 gives the circuit of one stage of a common drain amplifier (CD) using n-channel FET. Rs is the load impedance placed in the source circuit. Quite often a resistor Rd is placed in the drain circuit to further stabilize the operation of…

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Common Source Amplifier In this amplifier, input signal is applied between gate and source and the amplified output voltage is developed across a load resistor in the drain circuit. Thus, source is the common terminal between the input side and the output side. Figure 1 gives the circuit of one stage of common source amplifier (CS)  Amplifier using n-channel FET and with biasing arrangement. The typical component values are also shown in figure. This circuit is analogous to common emitter amplifier. On using p-channel FET, polarity of supply voltage is…

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Metal Oxide Semiconductor FET (MOSFET) MOSFET is of greater commercial importance than the junction FET. Types of MOSFET Enhancement MOSFETs and Depletion MOSFETs. Enhancement  Type MOSFET Figure 1 gives the cross-sectional view of a p-channel enhancement MOSFET. It consists of a lightly doped n-type substrate into which all diffused two highly dipped p + region spaced 10 to 20um apart. One region, say the left-hand region, acts as the source while the other region acts as the drain. A thin insulating layer of SiO2 of thickness 1000 to 2000 A…

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