ch07
Figure 7.1 The current mirror.
© 2000 Prentice Hall Inc.
Figure 7.2 Emitter follower with bias current source.
© 2000 Prentice Hall Inc.
Figure 7.3 The offset voltage can be reduced by cascading a complementary ( pnp ) emitter follower.
© 2000 Prentice Hall Inc.
Figure 7.4 Doubling the junction area of a BJT is equivalent to connecting two of the original BJTs in parallel.
© 2000 Prentice Hall Inc.
Figure 7.5 Current mirror for Examples~7.1 and 7.2.
© 2000 Prentice Hall Inc.
Figure 7.7 Output characteristic for the current mirror of Figure 7.5.
© 2000 Prentice Hall Inc.
Figure 7.8 Dynamic output resistance of the current mirror of Figure 7.5.
© 2000 Prentice Hall Inc.
Figure 7.9 Collector characteristic of Q
2
, illustrating the Early voltage.
© 2000 Prentice Hall Inc.
Figure 7.10 The Wilson current source, which has a high output resistance.
© 2000 Prentice Hall Inc.
Figure 7.11 The Widlar current source, which is useful for small currents.
© 2000 Prentice Hall Inc.
Figure 7.12 Typical biasing circuit for a bipolar IC.
© 2000 Prentice Hall Inc.
Figure 7.13 Answer for Exercise 7.2.
© 2000 Prentice Hall Inc.
Figure 7.14 JFET as a current source.
© 2000 Prentice Hall Inc.
Figure 7.15 NMOS current mirror.
© 2000 Prentice Hall Inc.
Figure 7.16 NMOS Wilson current source.
© 2000 Prentice Hall Inc.
Figure 7.17 Circuits for Exercise 7.4.
© 2000 Prentice Hall Inc.
Figure 7.18 Current versus voltage for the circuits of Figure 7.17.
© 2000 Prentice Hall Inc.
Figure 7.19 Dynamic resistance versus voltage for the circuits of Figure 7.17.
© 2000 Prentice Hall Inc.
Figure 7.20 One solution for Exercise 7.7.
© 2000 Prentice Hall Inc.
Figure 7.21 One solution for Exercise 7.8.
© 2000 Prentice Hall Inc.
Figure 7.22 Basic BJT differentiial amplifier.
© 2000 Prentice Hall Inc.
Figure 7.23a Basic BJT differential amplifier with waveforms.
© 2000 Prentice Hall Inc.
Figure 7.23b Basic BJT differential amplifier with waveforms.
© 2000 Prentice Hall Inc.
Figure 7.24 pnp emitter-coupled pair.
© 2000 Prentice Hall Inc.
Figure 7.25 Collector currents versus differential input voltage.
© 2000 Prentice Hall Inc.
Figure 7.26 Voltage transfer characteristic of the BJT differential amplifier.
© 2000 Prentice Hall Inc.
Figure 7.27 Differential amplifier with emitter degeneration resistors.
© 2000 Prentice Hall Inc.
Figure 7.28 Voltage transfer characteristic with emitter degeneration resistors. R
EF
= 40( V
T
/ I
EE
).
© 2000 Prentice Hall Inc.
Figure 7.29 Either a balanced or single-ended output is available\break from the differential amplifier.
© 2000 Prentice Hall Inc.
Figure 7.30 Emitter-coupled pair with current-mirror load.
© 2000 Prentice Hall Inc.
Figure 7.31 Answers for Exercise 7.10.
© 2000 Prentice Hall Inc.
Figure 7.32 Answers for Exercise 7.11.
© 2000 Prentice Hall Inc.
Figure 7.33 Small-signal equivalent circuit for the differential amplifier of Figure 7.27. ( R
EB is the output impedance of the current source I
EE
.)
© 2000 Prentice Hall Inc.
Figure 7.34 Half-circuit for a differential input signal.
© 2000 Prentice Hall Inc.
Figure 7.35 Small-signal equivalent circuit with a pure common-mode input signal.
© 2000 Prentice Hall Inc.
Figure 7.36 Half-circuit for a pure common-mode input signal.
© 2000 Prentice Hall Inc.
Figure 7.37 Emitter-coupled pair of Exercise 7.13.
© 2000 Prentice Hall Inc.
Figure 7.38 Addition of emitter followers to increase input impedance.
© 2000 Prentice Hall Inc.
Figure 7.39 First attempt in Example 7.4.
© 2000 Prentice Hall Inc.
Figure 7.40 Differential amplifier of Example7.4 using the Wilson current source.
© 2000 Prentice Hall Inc.
Figure 7.41 Differential amplifier of Example 7.4.
© 2000 Prentice Hall Inc.
Figure 7.42a Waveforms for the differential amplifier of Example 7.4.
© 2000 Prentice Hall Inc.
Figure 7.42b Waveforms for the differential amplifier of Example 7.4.
© 2000 Prentice Hall Inc.
Figure 7.42c Waveforms for the differential amplifier of Example 7.4.
© 2000 Prentice Hall Inc.
Figure 7.43 Source-coupled differential amplifier.
© 2000 Prentice Hall Inc.
Figure 7.44 Drain currents versus normalized input voltage.
© 2000 Prentice Hall Inc.
Figure 7.45 Differential output voltage versus normalized input voltage.
© 2000 Prentice Hall Inc.
Figure 7.46 Small-signal equivalent circuit for the source-coupled amplifier of Figure 7.43.
( Note: R
SB is the output resistance of the bias current source I .)
© 2000 Prentice Hall Inc.
Figure 7.47 Source-coupled differential pair of Example 7.5.
© 2000 Prentice Hall Inc.
Figure 7.48 Differential and common-mode voltage gains versus frequency for the circuit of Example 7.5.
© 2000 Prentice Hall Inc.
Figure 7.49 CMOS op amp.
© 2000 Prentice Hall Inc.
Figure 7.50 Small-signal equivalent circuit for the output stage consisting of M
7 and M
2
.
© 2000 Prentice Hall Inc.
Figure 7.51 Small-signal equivalent circuit for the source-coupled input stage.
© 2000 Prentice Hall Inc.
Figure 7.52 Test circuit for open-loop gain. The internal circuit for the op amp is shown in Figure 7.49.
© 2000 Prentice Hall Inc.
Figure 7.53 Open-loop gain versus frequency for the CMOS op amp.
© 2000 Prentice Hall Inc.
Figure 7.54 Unity-gain buffer amplifier of Exercise 7.16.
© 2000 Prentice Hall Inc.
Figure 7.55 A BJT op amp.
© 2000 Prentice Hall Inc.
Figure 7.56 Equivalent circuit for the first stage of Figure 7.52. R
EB
Q
8
. R i
= r p 3
+ r p 4 represents the output impedance of current sink is the differential input impedance of the second stage.
© 2000 Prentice Hall Inc.
