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10. Transistor Amplifiers and Switches. I. (. A). V. I. (. A). B. CEQ. B. V. = V. CE. CEQ. V. CE. Q. Q. I. I. I. BQ. BQ. B. V. V. BEQ. BEQ. V. (V). 0. 0. V. (V). BE. BE. V. V. BE. BE. (b) Interpretation of. h. (a) Interpretation of. h. r. e. ie. I.
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10 Transistor Amplifiers and Switches
I ( A) V I ( A) B CEQ B V = V CE CEQ V CE Q Q I I I BQ BQ B V V BEQ BEQ V (V) 0 0 V (V) BE BE V V BE BE (b) Interpretation of h (a) Interpretation of h r e ie I (mA) C I (mA) C I Q C I I BQ CQ I BQ I I I C CQ B Q V 0 CEQ (V) V CE 0 V V (V) V CEQ CE CE (c) Interpretation of h fe (d) Interpretation of h oe Figure 10.2 Graphical interpretation of h parameters
C + I B B V CE + V BE – – E C 1 h I fe B h oe h ie B + – h V re CE E Figure 10.3 h-parameter small-signal model for BJT
V CC R R 1 C C C r C o + C R B B S E r R v ( t ) i L out + ~ v ( t ) S – R R C – 2 E E Figure 10.7 The BJT common-emitter amplifier
V CC R R 1 C C C C + C R C B S R v ( t ) E L out + v ( t ) ~ S – – R R C 2 E E DC current AC current Figure 10.9 Effect of coupling capacitors on DC and AC current paths
R R C 1 V CC R 2 R E (a) DC circuit R S R R C L + _ ~ v ( t ) R || R S 1 2 (b) AC circuit Figure 10.10 DC and AC circuits for the common-emitter amplifier
I CQ + C R R B B C V CEQ I BQ _ E V BB V CC R E Figure 10.11 DC bias circuit for the common-emitter amplifier
V DD R 1 D R C S G C + _ ~ v ( t ) R 2 R R S L (a) Common-drain amplifier V DD R D R 1 C D R C S G + _ ~ v ( t ) R 2 C S R R L S (b) Common-source amplifier Figure 10.24 Typical common-drain and common-source MOSFET amplifiers
D D G g V = I m GS D + G V GS – S S MOSFET circuit symbol MOSFET small signal model Figure 10.27 MOSFET small-signal model
D + R R D G V 1 DSQ + – V S – GSQ R V 2 DD R V S DD Figure 10.28 DC circuit for the common-source amplifier
I D D + R G g V R R v ( t ) m GS D L L + + V v ( t ) ~ GS _ R R – – S 1 2 Figure 10.29 AC circuit for the common-source MOSFET amplifier
V DD R D 1 C R G C + S + ~ v ( t ) R 2 R v out S – Source follower I D + R G V DSQ + V – DD – V GSQ R V S GG R = R R G 1 2 R 2 = V V DD GG R R + 2 1 DC circuit Figure 10.30 MOSFET source follower and DC circuit
G D + V g V GS m GS – + R v S ~ _ G in + v R out S – Figure 10.31 AC equivalent circuit for the MOSFET source follower
V DD R D v out v in MOSFET inverter V = 5 V i GS D V 4 V B DD R 1 D – 3 V R D 2 V 1 V 0 1 2 3 4 5 v DS A (V) V = 5 V DD Switching characteristic Figure 10.50 MOSFET switching characteristic