1. ELECTRIC CIRCUITS EIGHTH EDITION
JAMES W. NILSSON
&
SUSAN A. RIEDEL
ELECTRIC CIRCUITS EIGHTH EDITION

2. CHAPTER 18
TWO-PORT CIRCUITS
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4. CONTENTS 18.1 The Terminal Equations 18.2 The Two-Port Parameters
18.3 Analysis of the Terminated Two-Port Circuit
18.4 Interconnected Two-Port Circuits
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5. 18.1 The Terminal Equations
Two-Port Model
The two-port model is used to describe the performance of a circuit in terms of the voltage and current at its input and output ports.
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6. 18.1 The Terminal Equations
The two-port building block
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7. 18.1 The Terminal Equations
The s-domain two-port basic building block
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8. 18.1 The Terminal Equations
The model is limited to circuits in which:
No independent sources are inside the circuit between the ports.
No energy is stored inside the circuit between the ports.
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9. 18.1 The Terminal Equations
The current into the port is equal to the current out of the port.
No external connections exist between the input and output ports.
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10. 18.1 The Terminal Equations
Two of the four terminal variables (V1, I1, V2, I2) are independent; therefore, only two simultaneous equations involving the four variables are needed to describe the circuit.
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11. 18.1 The Terminal Equations
The six possible sets of simultaneous equations involving the four terminal variables are called the z-, y-, a-, b-, h-, and g-parameter equations.
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12. 18.1 The Terminal Equations
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13. 18.1 The Terminal Equations
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14. 18.1 The Terminal Equations
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15. 18.1 The Terminal Equations
Parameter equations are written in
s domain.
dc values of parameters are obtained by setting s = 0, and sinusoidal steady-state values are obtained by setting s = j.
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16. 18.2 The Two-Port Parameters
Z – parameters :
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19. Y – parameters :
Transmission parameters :

20. H(hybrid) – parameters :
See :
word “immittance” denotes a quantity that is either an
impedance or an admittance.

23. See :

26. See :

29. The following relationship :

32. Reciprocal def. :
A two-port circuit is reciprocal if the interchange of an ideal voltage source at one port with an ideal ammeter at the other port produces the same ammeter reading.
A two-port circuit is reciprocal if the interchange of an ideal current source at one port with an ideal voltmeter at the other port produces the same voltmeter reading.
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33. 18.2 The Two-Port Parameters
A reciprocal two-port circuit is symmetric if its ports can be interchanged without disturbing the values of terminal currents and voltages.
A circuit with the voltage source and ammeter interchanged
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34. The following relationship :

35. 18.2 The Two-Port Parameters
Four examples of symmetric two-port circuits.
A symmetric tee
A symmetric pi
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36. 18.2 The Two-Port Parameters
A symmetric bridged tee
A symmetric lattice
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38. To illustrate how six characteristics are derived, we develop the expressions using z parameters to model two-port portion of circuit.
Next tables summarize the expressions involving y, a, b, h, and g parameters.
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39. Terminated two-port equations
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40. Terminated two-port equations
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41. Terminated two-port equations
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42. Derivation of parameters :
 z-parameters
 constraints

43. To find
See :    

44. Now,
See : 
Therefore,    

45. See :  
Then,

46. See : or 
Then,

47. See :
Therefore,

49. 2 ways exist.
1st, 
2nd,
see : 

50. see :
input port,

51. see :

52. 18.4 Interconnected Two-Port Circuits
Large networks can be divided into subnetworks by means of interconnected two-port models.
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53. 18.4 Interconnected Two-Port Circuits
(a) Cascade
(b) Series
(c) Parallel
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54. 18.4 Interconnected Two-Port Circuits
(d) Series-parallel
(e) Parallel-series
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56. See : 
Next,
See :
Therefore,

60. EE141

61. EE141
Home work
Prob
제출기한:
다음 요일 수업시간 까지
제출 기일을 지키지 않는 레포트는 사정에서
제외함
제출기한:
다음 요일 수업시간 까지
제출기일을 지키지않는 레포트는 사정에서 제외함
Prob
EE141

62. THE END
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