This preview shows pages 1–3. Sign up to view the full content.
704
Chapter
14
Operational Amplifiers
Problems
Section 14.1: Ideal Operational Amplifiers
P14.1.
What
are
the
c
haract
er
istics
of
an
id
eal
op
amp?
P14.2.
A real
amp
has
five terminals.
Name
probable
function
for
each
terminals.
P14.3.
A differential amplifier
input
voltages
v1
and
v2.
Give
definitions
differen
tial
voltage
commonmode
vo
ltage.
*P14.4.
The
a differential amplifier
(t)
=
0.5 cos(2000n
t)
+
20 cos(120n
v2
(t)
=
0.5
cos(2000n
+
Find expressions for
differential
components
signa
l.
P14.5.
Discuss
distinction
between
openloop
gain
closedloop gain.
Section 14.2: Inverting Amplifiers
*P14.6.
ste
ps
in
analyzing
amplifier
containing
ideal
P14.7.
do
we
mean
by
term
summing
point
constraint?
Does
it apply
when
posi
tive
feedback
is
present?
P14.8.
Draw
circuit
diagram
basic invert
in
g amplifier configuration. Give
expres
sion
closedloop voltage gain
terms
resistances, assuming
amp. Give expressions for
impedance
output
circuit.
P14.9.
Consider
circuit s
hown
Figure P14.9.
Sketch
Vin
v
0
to
scale versus time.
is ideal.
*P14.10.
Determine
shown
Figure Pl4.10, assuming
amp.
P14.11.
De
termin
e
th
e closedloop voltage gain
Figure P14.11, assuming
30kQ
+
lOkQ
2 sin(20007Tt)
Vin




Figure
P14.9
R
R
R




Figure P14.1 0
15
R
2R
R
Vjn
R






Figure P14.11
+
R




+
v
0
_1


+


P14.12.
inverting amplifier
Figure P14.12,
which
one
resistors
ha
s
be
en
replaced
with a
diode
.
Assume
amp,
positive,
a
diod
e cur
rent
given by
Equation
10.4, which
states
that
iD
=
Is
exp(vDfnVr).
Derive
*
Denotes
answers
contained in the
Student
Solutions
fil
es. See
App
endix F for
mor
e information
about
accessing the
Stud
e
nt
Solutions.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Documentexpression for
v
0
in terms of
Vin,
R, Is, n,
and
VT.
.
'o
R

Figure P14.12
+
v
Pl4.13.
Repeat Problem P14.12 by interchanging
the resistance
and the diode. Keep the
diode pointing toward the righthand side.
P14.14.
Consider the circuit shown in Figure P14.12,
with an unusual diode that has
in
=
Kv1
Derive an expression for
R,
K.
P14.15.
The op amp shown in Figure Pl4.15 is ideal,
except that the extreme output voltages
that it can produce are ±10 V. Determine
two possible values for each of the voltages
shown.
(Hint:
Notice that this circuit has
positive
feedback.)
2kn
1 kQ
2V
Figure P14.15
j_
P14.16.
Consider the inverting amplifier shown in
Figure P14.16. Assuming an ideal op amp,
solve for the currents and voltages shown.
According to Kirchhoff's current law, the
sum of the currents entering a closed surface
must equal the sum of the currents leav
ing. Explain how the law is satisfied for the
closed surface shown when we use a real op
amp in this circuit.
Problems
705
2kQ
___.
.
/
.....
'
I
\
i
1
>I
\ .1
......
1..
___
,
Closed
Surface
Figure P14.16
>
1kQ
Section 14.3: Noninverting Amplifiers
*Pl4.17.
Draw the circuit diagram of an opamp volt
age follower. What value is its voltage gain?
Input impedance? Output impedance?
*Pl4.18.
The voltage follower of Figure 14.12 on
page 673 has unity voltage gain so that
vin.
Why not simply connect the load
directly to the source, thus eliminating the
op amp? Give an example of a situation
in which the voltage follower is particularly
good compared with the direct connection.
P14.19.
Draw the circuit diagram of the basic non
inverting amplifier configuration. Give an
expression for the closedloop voltage gain
This is the end of the preview. Sign up
to
access the rest of the document.
 Spring '09
 Mechatronics

Click to edit the document details