1. Overview The preparatory work for designing a single-stage power amplifier with a Mitsubishi MGF0909A will be done in this example. The main steps in this initial phase are to 1.Open a new circuit file with the required substrate, terminations and passband specification. 2.Fit a small-signal model to the S-parameters of the MGF0909A transistor. The dc operating point and the four boundary lines defining the allowable load-line area on the dc I/V-plane must also be specified when the model is fitted. The model and the load-line constraints are used to find the optimum load-line for maximum output power, as well as analysis of the power performance. 3.The transistor and the lines defining the connections to be made to the transistor will be added to the circuit file. Note that the drain and gate flanges of the transistor also behave like transmission-lines and that these lines do not launch immediately onto the microstrip substrate. The substrate for these sections is actually air (er=1). The substrate height is also different from that of the microstrip substrate (a recess is required in the box to mount the power transistor).

2. Open a new circuit

3. Select the document type

4. Select the substrate type

5. Specify the terminations to be used

6. Specify the number of passbands

7. Specify the analysis frequency range and the passband

8. Specify the microstrip substrate

9. A name must be specified for the new circuit

10. The name specified for the circuit

11. The startup schematic of the new circuit

12. Select the FET Model Command from the Analysis Menu

13. The dialog for opening the S-parameter data file of the transistor to be used is presented

14. The mgf0909a.s2p data file is selected

15. An Amplifer Design Wizard (ADW) label must be specified for the set of S-parameters

16. Choose the Initialize Command to fit a basic model to the specified set of S-parameters

17. The Error Type, Target Parameters, Weight Factors and Frequency Range specified

18. The frequency range over which the parameters must be fitted initially

19. The Error Type, Target Parameters, Weight Factors and Frequency Range specified

20. The S-parameters of the model (single color traces) are compared with the specified parameters (mixed color traces)

21. Bounds are set before optimizing the component values

22. The trans-conductance is constrained as shown

23. Rds is constrained too

24. The constraints set for Rg

25. The constraints set for Rd

26. The constraints set for Rs

27. Lumped package components can be added on this page

28. A small value was specified for each of the elements

29. The optimization option was set for each of the components

30. Select the Optimization Command on the Intrinsic Model Page

31. The frequency range is set to the full range

32. The Least-Square Error and the Y-parameters are selected again

33. The fit after optimization

34. Zooming in to view the fit in s21 more closely

35. Selecting the L1 error and the S-parameters to be used in the next optimization cycle

36. The fit obtained

37. Viewing the fit in s11 and s22 more closely

38. The fit in s21 and s12

39. The intrinsic elements fitted

40. The package elements fitted

41. The I/V Curve Boundaries Page

42. The boundary lines and the operating point specified

43. A rendering of the specifications

44. Select the OK Command on the Intrinsic Model Page to save the model fitted

45. The Twoport Command is selected to insert the transistor into the circuit

46. The transistor will be inserted between the two lines

47. The insert position is marked with the vertical line shown

48. The name of the S-parameter data file is specified

49. The next page of the Twoport Wizard

50. The page for specifying the artwork vectors and the transistor configuration

51. The specifications made for the MGF0909A

52. A rendering of the artwork vector specified

53. The twoport has been inserted into the schematic

54. The command to insert a microstrip line into the schematic is selected

55. The line will be inserted to the right of the input line

56. The position of interest is marked with the vertical line

57. The dimensions of the line and the substrate to be used are specified

58. The line inserted

59. A line will be inserted to the right of the transistor next

60. The position of interest is marked in the circuit file

61. The parameters of microstrip line to be inserted

62. The electrical parameters of the inserted line

63. The artwork will be displayed next

64. The artwork of the circuit

65. The line editing command will be selected next

66. The line editing dialog box

67. The input line was selected for editing

68. The line length is set at 2mm

69. The shortened input line

70. The output line will be shortened too

71. The line length is again set at 2mm

72. The shortened output line

73. Preparing to insert a line

74. Saving the artwork changes made

75. A line will be inserted between the two lines on the input side

76. The new line

77. A second new line was inserted into the schematic

78. Two new lines were inserted on the output side too

79. The modified schematic is saved

80. The artwork will be edited again

81. The width of the selected line will be reduced

82. The artwork edited to prepare for the matching networks to be synthesized

83. Matching networks will be designed in the next example to maximize the output power and the match the input of the transistor. Leveling the gain instead of matching the input will also be considered. Next Phase of the Design