VIDEO
C
0
U
R
S
E
M
A
N
U
A
I
Operational
Amplifier
Compensation
(continued)
13
L
13-2
Electronic Feedback Systems
0._A_,_Exam_
Blackboard 13.1
Viewgraph 13.1
Approximation
Uncompensated
(including loading
of compensating
network)
t
M
Uncom-
- 9(
-
18(
- 271
Unloaded open-loop transfer
function for compensation
that includes a zero.
(~o
OperationalAmplifier Compensation (cont.)
Viewgraph 13.2
Compensating network
Output
from
Input to
second
stage
second
agO Va
rs + 1
Input impedance
of second stage
Model for second stage of a
two-stage amplifier.
Viewgraph 13.3
7Oc
V.'I
Circuit used to evaluate slowrolloff compensation.
13-3
13-4
Electronic Feedback Systems
Viewgraph 13.4
R
aY2
,
C
0
Y2
R
a
C
a
R
C
4
-0
0-
aC
aR
a2C
a 2R
eA
ev
Network used to approximate
an admittance proportional to
Viewgraph 13.5
s
Comparison of approximate openloop transfer functions for three
types of compensation.
107
106
tM 10
104
103
100
1
11
1
1
10
100
1
103
104
~oU
0 t-
$
-
U
-900
1
a'
a
450
10
100
103
104
10,
106
to(rad/sec)---
107
-
-
OperationalAmplifier Compensation (cont.)
Demonstration Photograph
13.1
Slow-roll-off compensation
demonstration
Demonstration Photograph
__13.2
Slow-roll-off network
-I-
13-5
13-6
Electronic Feedback Systems
Comments
Our discussion of minor-loop compensation tailored to specific
applications is continued. We find that if a zero is added to the
open- (major-) loop transmission at an appropriate frequency,
acceptable stability can be maintained when an additional pole (for
example, from capacitive loading) occurs. This type of compensation requires specific information concerning the location of the
additional pole.
Conversely, compensation that rolls off more slowly than 1/s
is advantageous when it is expected that the additional pole will be
located over a range of frequencies.
Reading
Textbook: Sections 13.3.4 and 13.3.5.
Problems
Problem 13.1 (P13.10)
Problem 13.2 (P13.11)
MIT OpenCourseWare
http://ocw.mit.edu
RES.6-010 Electronic Feedback Systems
Spring 2013
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