© 2000 Prentice Hall Inc. Figure 5.1 n-Channel enhancement MOSFET showing channel length L and channel width W.

© 2000 Prentice Hall Inc.

Figure 5.1 n-Channel enhancement MOSFET showing channel length L and channel width W.


Figure 5.2 Circuit symbol for an enhancement-mode n-channel MOSFET.


Figure 5.3 For vGS < Vto the pn junction between drain and body is reverse biased and iD=0.


Figure 5.4 For vGS >Vto a channel of n-type material is induced in the region under the gate. As vGS increases, the channel becomes thicker. For small values of vDS ,iD is proportional to vDS.

The device behaves as a resistor whose value depends on vGS.


Figure 5.5 As vDS increases, the channel pinches down at the drain end and iD increases more slowly. Finally for vDS> vGS -Vto, iD becomes constant.


Figure 5.6 Characteristic curves for an NMOS transistor.


Figure 5.7 This circuit can be used to plot drain characteristics.


Figure 5.11 Drain characteristics for Example 5.2.


Figure 5.12 Diodes protect the oxide layer from destruction by static electric charge.


Figure 5.13 Simple NMOS amplifier circuit.


Figure 5.14 Drain characteristics and load line for the circuit of Figure 5.13.


Figure 5.15 vDS versus time for the circuit of Figure 5.13.


Figure 5.16 Fixed- plus self-bias circuit.


Figure 5.17 Graphical solution of Equations (5.17) and (5.18).


Figure 5.18 Fixed- plus self-biased circuit of Example 5.3.


Figure 5.20 The more nearly horizontal bias line results in less change in the Q-point.


Figure 5.21 Illustration of the terms in Equation (5.20).


Figure 5.22 Small-signal equivalent circuit for FETs.


Figure 5.23 FET small-signal equivalent circuit that accounts for the dependence of iD on vDS.


Figure 5.24 Determination of gm and rd. See Example 5.5.


Figure 5.25 Common-source amplifier.


Figure 5.26 Small-signal equivalent circuit for the common-source amplifier.


Figure 5.27 Circuit used to find $R_o$.


Figure 5.28 Common-source amplifier.


Figure 5.31 vo(t) and vin(t) versus time for the common-source amplifier of Figure 5.28.


Figure 5.32 Gain magnitude versus frequency for the common-source amplifier of Figure 5.28.


Figure 5.33 Source follower.


Figure 5.34 Small-signal ac equivalent circuit for the source follower.


Figure 5.35 Equivalent circuit used to find the output resistance of the source follower.


Figure 5.36 Common-gate amplifier.


Figure 5.37 See Exercise 5.12.


Figure 5.38 n-Channel JFET.


Figure 5.39 The nonconductive depletion region becomes thicker with increased reverse bias. (Note: The two gate regions of each FET are connected to each other.)


Figure 5.40 Circuit for the discussion of drain characteristics of the n-channel JFET.


Figure 5.41 Drain current versus drain-to-source voltage for zero gate-to-source voltage.


Figure 5.42 n-Channel FET for vGS = 0.


Figure 5.43 Typical drain characteristics of an n-channel JFET.


Figure 5.44 If vDG exceeds the breakdown voltage VB, drain current increases rapidly.


Figure 5.45 See Exercise 5.14.


Figure 5.46 n-Channel depletion MOSFET.


Figure 5.47 Drain current versus vGS in the saturation region for n-channel devices.


Figure 5.48 p-Channel FET circuit symbols. These are the same as the circuit symbols for n-channel devices, except for the directions of the arrowheads.


Figure 5.49 Drain current versus vGS for several types of FETs. iD is referenced into the drain terminal for n-channel devices and out of the drain for p-channel devices.

© 2000 Prentice Hall Inc. Figure 5.1 n-Channel enhancement MOSFET showing channel length L and channel width W.

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