Download presentation

Presentation is loading. Please wait.

Published byMagdalene Dixon Modified about 1 year ago

1
Lecture 5 Source Transformation Thevenin Equivalent Circuit Norton Equivalent Circuit

2
Circuit Techinques Ohm’s Law P=VI KCL, KVL Voltage/current divider Series/parallel resistance Mesh/Nodal Analysis Source Transformation Thevenin/Norton Equivalent Circuit Superposition Principle Maximum Power Transfer

3
Source Transformation Show that i S =v S /R for any R L

4
Thevenin Equivalent Circuit

5
Determine the Thevenin Voltage (V Th ) If R L =∞ (load across a-b is removed), then V ab =V TH – R TH does not play a role!

6
3 Bit Digital to Analog Converter 741 Op-Amp Chapter 5

7
Sample DAC Waveform Digital Input DAC Output

8
Applications Most modern audio signals are stored in digital form (e.g. MP3 and CDs) and in order to be heard through speakers they must be converted into an analog signal

9
Thevenin Equivalent Circuit

10
Determine V TH

11
Methods of Finding R TH R TH =V TH /i SC – If R L =0, the short circuit current from a to b (i.e. i ab ) should equal to i sc =V Th /R TH. – So R TH =V Th /i sc If the network contains only independent sources: – Deactivate a voltage source by replacing it with a short – Deactivate a current source by replacing it with an open If the network contains dependent sources – Apply a test source

12
Calculate the Thevenin Resistance R TH

13
If the network contains only independent sources R TH ?

14
R TH

15
Methods of Finding R TH R TH =V TH /i SC – If R L =0, the short circuit current from a to b (i.e. i ab ) should equal to i sc =V Th /R TH. – So R TH =V Th /i sc If the network contains only independent sources: – Deactivate a voltage source by replacing it with a short – Deactivate a current source by replacing it with an open If the network contains dependent sources – Apply a test source

16
Degenerated Common Emitter Amplifier (from last lecture)

17
What if we drive the base with a small signal? Vin, m=1 mV Vout, m=46 mV

18
Mesh Analysis (Last Lecture) n e =2 essential nodes b e =3 essential branches 3-(2-1)=2 equations

19
Mesh Analysis (Last Lecture) 12 Clockwise around loop 1: +V in -i 1 r π -(i 1 +i 2 )R E =0 Counter-clockwise around loop 2: i 2 =g m i 1 r π V out =-i 2 R C Loop 1: clockwise Loop 2: counter-clockwise

20
Mesh Analysis (Details)

21
Determine R TH when a Dependent Source is Present ITIT

22
Methods of Finding R TH R TH =V TH /i SC – If R L =0, the short circuit current from a to b (i.e. i ab ) should equal to i sc =V Th /R TH. – So R TH =V Th /i sc If the network contains only independent sources: – Deactivate a voltage source by replacing it with a short – Deactivate a current source by replacing it with an open If the network contains dependent sources – Apply a test source

23
Another Way to Find R TH i sc

24
R TH Calculation i SC =10V/100 KOhms=0.1 mA V TH =10V/2=5V R TH =V TH /i SC =5V/0.1 mA=50 KOhms

25
Norton Equivalent Circuit A Norton Equivalent circuit consists of – Short-Circuit Current – Norton Equivalent Resistance, which is equal to Thevenin Equivalent Resistance

26
Getting A Norton Equivalent Circuit from Thevenin Equivalent Circuit Norton Equivalent Circuit Thevenin Equivalent Circuit V TH R TH I N =V TH /R TH

27
Derivation of Norton Equivalent Circuit V TH R TH I N =V TH /R TH

28
Extra Credit Assignment Derive

29
More about the Extra Credit Assignment

30
Extra Slides on Thevenin

31
Determine v ab Show that V TH = v ab

32
Determine i SC and R TH

33
Example 4.10 Determine the Thevenin Equivalent Voltage

34
Example Determine the short circuit current 2.Determine R TH

35
Slides on Source Transformation

36
R TH

37
Application Determine whether the 6V source is absorbing or delivering the power.

38
Step-by-step simplification

39
Redundant Resistor (1) Prove that the left circuit and the right circuit are equivalent for any load resistor.

40
Redundant Resistor (2) Prove that the left circuit and the right circuit are equivalent for any load resistor.

41
Example 4.9

42
Simplified Circuit

Similar presentations

© 2016 SlidePlayer.com Inc.

All rights reserved.

Ads by Google