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Chapter Five The Field-Effect Transistor
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Figure 6—2 A three-terminal nonlinear device that can be controlled by the voltage at the third terminal v G : (a) biasing circuit; (b) I–V characteristic and load line. If v G = 0.5 V, the d-c values of I D and V D are as shown by the dashed lines.
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Figure 6—3 Simplified cross-sectional view of a junction FET: (a) transistor geometry; (b) detail of the channel and voltage variation along the channel with V G = 0 and small I D.
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Figure 6—4 Depletion regions in the channel of a JFET with zero gate bias for several values of V D : (a) linear range; (b) near pinch-off; (c) beyond pinch-off.
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Figure 6—5 Effects of a negative gate bias: (a) increase of depletion region widths with V G negative; (b) family of current– voltage curves for the channels as V G is varied.
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Figure 6—11 n-channel MOSFET cross-sections under different operating conditions: (a) linear region for V G > V T and V D V T and V D = (V G 2 V T ); (c) strong saturation, V G > V T and V D > (V G 2 V T ).
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Figure 6—27 Drain current–voltage characteristics for enhancement transistors: (a) for n-channel V D, V G, V T, and I D are positive; (b) for p-channel all these quantities are negative.
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Figure 6—28 Linear region transfer characteristics: (a) plot of drain current versus gate voltage for MOSFETs in the linear region; (b) transconductance as a function of gate bias.
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Figure 6—29 Saturation region transfer characteristics: plot of square root of the drain current versus gate voltage for MOSFETs.
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Figure 6—39 Equivalent circuit of a MOSFET, showing the passive capacitive and resistive components. The gate capacitance C i is the sum of the distributed capacitances from the gate to the source-end of the channel (C GS ) and the drain-end (C GD ). In addition, we have an overlap capacitance (where the gate electrode overlaps the source/drain junctions) from the gate-to-source (C OS ) and gate-to-drain (C OD ). C OD is also known as the Miller overlap capacitance. We also have p-n junction depletion capacitances associated with the source (C JS ) and drain (C JD ). The parasitic resistances include the source/drain series resistances (R S and R D ), and the resistances in the substrate between the bulk contact and the source and drain (R BS and R BD ). The drain current can be modeled as a (gate) voltage-controlled constant-current source.
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Figure 5.24 (a) An NMOS common-source circuit and (b) the NMOS circuit for Example 5.3
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Figure 5.25 (a) A PMOS common-source circuit, (b) results when saturation-region bias assumption is incorrect, and (c) results when nonsaturation-region bias assumption is correct
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Figure 5.28 Transistor characteristics, v DS (sat) curve, load line, and Q-point for the NMOS common-course circuit in Figure 5.24 (b)
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Figure 5.29 NMOS common-source circuit with source resistor
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Figure 5.35 Circuit with enhancement load devices and NMOS driver
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Figure 5.36 Voltage transfer characteristics of NMOS inverter with enhancement load device
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Figure 5.37 (a) Depletion-mode NMOS device with the gate connected to the source and (b) current-voltage characteristics
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Figure 5.39 Circuit with depletion load device and NMOS driver
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Figure 5.40 Voltage transfer characteristics of NMOS inverter with depletion load device
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Figure 5.47 (a) An NMOS common-source circuit with a time-varying signal coupled to the gate and (b) transistor characteristics, load line, and superimposed sinusoidal signals
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Chapter Six Basic FET Amplifiers
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Figure 6.13 Common-source circuit with voltage divider biasing and coupling capacitor
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Figure 6.14 Small-signal equivalent circuit, assuming coupling capacitor acts as a short circuit
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Figure 6.17 DC load line and transition point for NMOS circuit shown in Figure 6.16
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Figure 6.19 Small-signal equivalent circuit of NMOS common-source amplifier with source resistor
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Figure 6.28 NMOS source-follower or common-drain amplifier
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Figure 6.29 (a) Small-signal equivalent circuit of NMOS source-follower and (b) small-signal equivalent circuit of NMOS source-follower with all signal grounds at a common point
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Figure 6.34 Common-gate circuit
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Figure 6.35 Small-signal equivalent circuit of common-gate amplifier
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Figure 6.39 (a) NMOS amplifier with enhancement load device; (b) driver transistor characteristics and enhancement load curve with transition point
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Figure 6.39c Voltage transfer characteristics of NMOS amplifier with enhancement load device
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Figure 6.43 (a) NMOS amplifier with depletion load device; (b) driver transistor characteristics and depletion load curve, with transition points
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Figure 6.43c (c) voltage transfer characteristics
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Figure 6.45 (a) CMOS common-source amplifier; (b) PMOS active load i-v characteristic, (c) driver transistor characteristics with load curve, (d) voltage transfer characteristics
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Figure 6.50 NMOS cascode circuit
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Figure 6.52 Small-signal equivalent circuit of NMOS cascode circuit
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