besta untitled
TRANSCRIPT
-
8/18/2019 besta Untitled
1/34
Lecture 15 16
1. Feedback advantages
2. feedback disadvantages3 . Feedback topologies
Usman JavaidLecturer
Electrical Engineering Department
CIIT Islamabad
-
8/18/2019 besta Untitled
2/34
Feedback advantages
Noise sensitivity• Noise ?
-
8/18/2019 besta Untitled
3/34
-
8/18/2019 besta Untitled
4/34
-
8/18/2019 besta Untitled
5/34
-
8/18/2019 besta Untitled
6/34
-
8/18/2019 besta Untitled
7/34
-
8/18/2019 besta Untitled
8/34
Gain sensitivity
CONCLUSION
Percentage change in closed loop
Gain is less than the percentage
Change in open loop gain by a
Factor of (1 + AB )
-
8/18/2019 besta Untitled
9/34
-
8/18/2019 besta Untitled
10/34
Ideal Feedback topologies
-
8/18/2019 besta Untitled
11/34
-
8/18/2019 besta Untitled
12/34
Output impedance
-
8/18/2019 besta Untitled
13/34
-
8/18/2019 besta Untitled
14/34
Series-shunt configuration
-
8/18/2019 besta Untitled
15/34
Finding Input impedance
-
8/18/2019 besta Untitled
16/34
Finding output impedance
-
8/18/2019 besta Untitled
17/34
-
8/18/2019 besta Untitled
18/34
Series-series Feedback topology
-
8/18/2019 besta Untitled
19/34
Shunt-shunt configuration
-
8/18/2019 besta Untitled
20/34
Summary
-
8/18/2019 besta Untitled
21/34
Lecture 17
1 . Feedback topologies
2. op-amp Series Shunt feedback3. op-amp shunt series feedback
Usman JavaidLecturer
Electrical Engineering Department
CIIT Islamabad
-
8/18/2019 besta Untitled
22/34
Series shunt Feedback
-
8/18/2019 besta Untitled
23/34
Calculating feedback transfer function
By comparison
Calculate feedback gain
By Voltage divider rule
-
8/18/2019 besta Untitled
24/34
Calculating gain using feedback
concepts
-
8/18/2019 besta Untitled
25/34
-
8/18/2019 besta Untitled
26/34
Input and output impedances
-
8/18/2019 besta Untitled
27/34
-
8/18/2019 besta Untitled
28/34
Op-amp shunt-series feedback
-
8/18/2019 besta Untitled
29/34
Feedback transfer function
For very large open loop gain it becomes
And feedback transfer function is
-
8/18/2019 besta Untitled
30/34
Equivalent shunt-series configuration
Solve for Ifb and put in
-
8/18/2019 besta Untitled
31/34
-
8/18/2019 besta Untitled
32/34
Equivalent Series-series configuration
Backward substitution yields
-
8/18/2019 besta Untitled
33/34
-
8/18/2019 besta Untitled
34/34
Equivalent Model