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OP Amp

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Figure 2.25 Bode plot of open-loop gain for a typical op amp. ... Figure 2.40 Bode plot of the gain magnitude for the ... Figure 2.64b Comparative Bode plots. ... – PowerPoint PPT presentation

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Title: OP Amp


1
OP Amp
2
Figure 2.3 Op-amp symbol showing power supplies.
3
Figure 12.2 Transfer characteristics of ideal
comparators.
4
Figure 2.1 Circuit symbol for the op amp.
5
Figure 2.2 Equivalent circuit for the ideal op
amp. AOL is very large (approaching infinity).
6
Fig. 1.14 (a) An amplifier transfer
characteristic that shows considerable
nonlinearity. (b) To obtain linear operation the
amplifier is biased as shown, and the signal
amplitude is kept small.
7
Figure 2.4 Inverting amplifier.
8
Fig. 2.5 Analysis of the inverting
configuration
9
Figure 2.11 Noninverting amplifier.
10
Figure 2.26 Noninverting amplifier.
11
Figure 2.12 Voltage follower.
12
Figure 2.13 Inverting or noninverting amplifier.
See Exercise 2.4.
13
Figure 2.7 Summing amplifier. See Exercise 2.1.
14
Figure 2.53 Differential amplifier.
15
Figure 2.6 An inverting amplifier that achieves
high gain with a smaller range of resistor values
than required for the basic inverter.
16
Figure 2.59 Variable-gain amplifier. See
Exercise 2.21.
17
Figure 2.15 Circuit for Exercise 2.6.
18
Figure 2.20 If low-value resistors are used, an
impractically large current is required.
19
Figure 2.54 Instrumentation-quality differential
amplifier.
20
Fig. 2.25 (a) A popular circuit for an
instrumentation amplifier. (b) Analysis of the
circuit in (a) assuming ideal op-amps. (c) To
make the gain variable, R1 is implemented as the
series combination of a fixed resister R1f and a
variable resistor R1v. Resistor R1f ensures that
the maximum available gain is limited.
21
Figure 2.23 Amplifier designed in Example 2.4.
22
Fig. 2.29 (a) Unity-gain follower. (b) Input
step waveform. (c) Linearly rising output
waveform obtained when the amplifier is slew-rate
limited. (d) Exponentially rising output
waveform obtained when V is sufficiently small so
that the initial slope (wtV) is smaller then or
equal to SR.
23
Figure 2.6 An inverting amplifier that achieves
high gain with a smaller range of resistor values
than required for the basic inverter.
24
Fig. 2.26 Open-loop gain of a typical
general-purpose internally compensated op amp.
25
Figure 1.45 Electrocardiographs encounter large
60-Hz common-mode signals.
26
Figure 1.47 Setup for measuring differential
gain. Ad vo/vid.
27
Figure 1.44 The input sources vi1 and vi2 can be
replaced by the equivalent sources vicm and vid.
28
Fig. 2.24 Representation of the common-mode and
differential components of the input signal to a
difference amplifier. Note that v1 vCM - vd/2
and v2 vCM vd/2.
29
Figure 2.17 The resistance of the larger square
is the same as the resistance of each of the
smaller squares.
30
Figure 2.19 IC resistors are often folded to keep
the distance between the contacts smaller.
31
Figure 2.22 To attain large input resistance with
moderate resistances for an inverting amplifier,
we cascade a voltage follower with an inverter.
32
Figure 2.21 If very high value resistors are
used, stray capacitance can couple unwanted
signals into the circuit.
33
Figure 2.25 Bode plot of open-loop gain for a
typical op amp.
34
Figure 2.27 Bode plots for Example 2.5.
35
Figure 2.28 For a real op amp, clipping occurs if
the output voltage reaches certain limits.
36
Figure 2.30 Output of the circuit of Figure 2.29
for RL 10kV and Vs max 5V.
37
Figure 2.31 Output of the circuit of Figure 2.29
for RL 10kV and vs(t) 2.5 sin (105p t).
38
Figure 2.33 Current sources and a voltage source
model the dc imperfections of an op amp.
39
Figure 2.34b Circuit of Example 2.10.
40
Figure 2.34c Circuit of Example 2.10.
41
Figure 2.34d Circuit of Example 2.10.
42
Figure 2.64c Comparative Bode plots.
43
Fig. 2.30 Effect of slew-rate limiting on output
sinusoidal waveforms.
44
Figure 2.36 Noninverting amplifier, including
resistor R to balance the effects of the bias
currents. See Exercise2.17.
45
Figure 2.40 Bode plot of the gain magnitude for
the circuit of Figure 2.37.
46
Figure 2.42 Noninverting amplifier used to
demonstrate nonlinear effects.
47
Figure 2.45 Output of the circuit of Figure 2.42
for RL 10kV and Vim 5V.
48
Figure 2.47 Inverting amplifier.
49
Figure 2.49 Summing amplifier.
50
Figure 2.50 Noninverting amplifier. This circuit
approximates an ideal voltage amplifier.
51
Figure 2.48 Ac-coupled inverting amplifier.
52
Figure 2.51 Ac-coupled noninverting amplifier.
53
Figure 2.52 Ac-coupled voltage follower with
bootstrapped bias resistors.
54
Figure 2.55 Voltage-to-current converter
(transconductance amplifier).
55
Figure 2.56 Voltage-to-current converter with
grounded load (Howland circuit).
56
Figure 2.57 Current-to-voltage converter
(transresistance amplifier).
57
Figure 2.58 Current amplifier.
58
Figure 2.60 Integrator.
59
Figure 2.64a Comparative Bode plots.
60
Figure 2.61 Square-wave input signal for
Exercise 2.24.
61
Figure 2.62 Answer for Exercise 2.24a.
62
Figure 2.63 Differentiator.
63
Figure 2.64b Comparative Bode plots.
64
Figure 12.5 The input voltage vin is compared to
the reference voltage Vr.
65
Figure 12.3 Transfer characteristic of a real
comparator.
66
Figure 12.6 Noise added to the input signal can
cause undesired transitions in the output signal.
67
Figure 12.8 Noninverting Schmitt trigger.
68
Figure 2.10a Schmitt trigger circuit and
waveforms.
69
Figure 2.10b Schmitt trigger circuit and
waveforms.
70
Figure 12.7 A Schmitt trigger is formed by using
positive feedback with a comparator.
71
Figure 12.9 Schmitt triggers that can be
designed to have specified thresholds.
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