1. Single-Stage Integrated- Circuit Amplifiers1

2. Table 6.3
Microelectronic Circuits - Fifth Edition Sedra/Smith

3. sedr42021_0601.jpg
Figure 6.1 The intrinsic gain of the MOSFET versus bias current ID. Outside the subthreshold region, this is a plot of for the case: mnCox = 20 mA/V2, V9A = 20 V/mm, L = 2 mm, and W = 20 mm.
Microelectronic Circuits - Fifth Edition Sedra/Smith

4. sedr42021_0602a.jpg
Figure 6.2 Frequency response of a CS amplifier loaded with a capacitance CL and fed with an ideal voltage source. It is assumed that the transistor is operating at frequencies much lower than fT, and thus the internal capacitances are not taken into account.
Microelectronic Circuits - Fifth Edition Sedra/Smith

5. sedr42021_0603.jpg
Figure 6.3 Increasing ID or W/L increases the bandwidth of a MOSFET amplifier loaded by a constant capacitance CL.
Microelectronic Circuits - Fifth Edition Sedra/Smith

6. sedr42021_0604.jpg
Figure 6.4 Circuit for a basic MOSFET constant-current source.
Microelectronic Circuits - Fifth Edition Sedra/Smith

7. sedr42021_0605.jpg Figure 6.5 Basic MOSFET current mirror.
Microelectronic Circuits - Fifth Edition Sedra/Smith

8. sedr42021_0606.jpg
Figure 6.6 Output characteristic of the current source in Fig. 6.4 and the current mirror of Fig. 6.5 for the case Q2 is matched to Q1.
Microelectronic Circuits - Fifth Edition Sedra/Smith

9. sedr42021_0607.jpg Figure 6.7 A current-steering circuit.
Microelectronic Circuits - Fifth Edition Sedra/Smith

10. sedr42021_0608.jpg Figure 6.8 The basic BJT current mirror.
Microelectronic Circuits - Fifth Edition Sedra/Smith

11. sedr42021_0609.jpg
Figure 6.9 Analysis of the current mirror taking into account the finite b of the BJTs.
Microelectronic Circuits - Fifth Edition Sedra/Smith

12. sedr42021_0610.jpg Figure 6.10 A simple BJT current source.
Microelectronic Circuits - Fifth Edition Sedra/Smith

13. sedr42021_0611.jpg
Figure Generation of a number of constant currents of various magnitudes.
Microelectronic Circuits - Fifth Edition Sedra/Smith

14. sedr42021_e0608.jpg
Figure E6.8
Microelectronic Circuits - Fifth Edition Sedra/Smith

15. sedr42021_0612.jpg
Figure Frequency response of a direct-coupled (dc) amplifier. Observe that the gain does not fall off at low frequencies, and the midband gain AM extends down to zero frequency.
Microelectronic Circuits - Fifth Edition Sedra/Smith

16. sedr42021_0613.jpg
Figure Normalized high-frequency response of the amplifier in Example 6.5.
Microelectronic Circuits - Fifth Edition Sedra/Smith

17. sedr42021_0614a.jpg
Figure Circuits for Example 6.6: (a) high-frequency equivalent circuit of a MOSFET amplifier; (b) the equivalent circuit at midband frequencies; (c) circuit for determining the resistance seen by Cgs; and (d) circuit for determining the resistance seen by Cgd.
Microelectronic Circuits - Fifth Edition Sedra/Smith

18. sedr42021_0615.jpg Figure 6.15 The Miller equivalent circuit.
Microelectronic Circuits - Fifth Edition Sedra/Smith

19. sedr42021_0616a.jpg Figure 6.16 Circuit for Example 6.7.
Microelectronic Circuits - Fifth Edition Sedra/Smith

20. sedr42021_e0613.jpg
Figure E6.13
Microelectronic Circuits - Fifth Edition Sedra/Smith

21. sedr42021_0617a.jpg
Figure (a) Active-loaded common-source amplifier. (b) Small-signal analysis of the amplifier in (a), performed both directly on the circuit diagram and using the small-signal model explicitly.
Microelectronic Circuits - Fifth Edition Sedra/Smith

22. sedr42021_0618a.jpg
Figure The CMOS common-source amplifier; (a) circuit; (b) i–v characteristic of the active-load Q2; (c) graphical construction to determine the transfer characteristic; and (d) transfer characteristic.
Microelectronic Circuits - Fifth Edition Sedra/Smith

23. sedr42021_0619a.jpg
Figure (a) Active-loaded common-emitter amplifier. (b) Small-signal analysis of the amplifier in (a), performed both directly on the circuit and using the hybrid-p model explicitly.
Microelectronic Circuits - Fifth Edition Sedra/Smith

24. sedr42021_0620.jpg
Figure High-frequency equivalent-circuit model of the common-source amplifier. For the common-emitter amplifier, the values of Vsig and Rsig are modified to include the effects of rp and rx; Cgs is replaced by Cp, Vgs by Vp, and Cgd by Cm.
Microelectronic Circuits - Fifth Edition Sedra/Smith

25. sedr42021_0621.jpg
Figure Approximate equivalent circuit obtained by applying Miller’s theorem while neglecting CL and the load current component supplied by Cgd. This model works reasonably well when Rsig is large and the amplifier high-frequency response is dominated by the pole formed by Rsig and Cin.
Microelectronic Circuits - Fifth Edition Sedra/Smith

26. sedr42021_0622a.jpg
Figure Application of the open-circuit time-constants method to the CS equivalent circuit of Fig
Microelectronic Circuits - Fifth Edition Sedra/Smith

27. sedr42021_0623.jpg
Figure Analysis of the CS high-frequency equivalent circuit.
Microelectronic Circuits - Fifth Edition Sedra/Smith

28. sedr42021_0624.jpg
Figure The CS circuit at s 5 sZ. The output voltage Vo 5 0, enabling us to determine sZ from a node equation at D.
Microelectronic Circuits - Fifth Edition Sedra/Smith

29. sedr42021_0625a.jpg
Figure (a) High-frequency equivalent circuit of the common-emitter amplifier. (b) Equivalent circuit obtained after the Thévenin theorem is employed to simplify the resistive circuit at the input.
Microelectronic Circuits - Fifth Edition Sedra/Smith

30. sedr42021_0626a.jpg
Figure (a) High-frequency equivalent circuit of a CS amplifier fed with a signal source having a very low (effectively zero) resistance. (b) The circuit with Vsig reduced to zero. (c) Bode plot for the gain of the circuit in (a).
Microelectronic Circuits - Fifth Edition Sedra/Smith

31. sedr42021_0627a.jpg
Figure (a) Active-loaded common-gate amplifier. (b) MOSFET equivalent circuit for the CG case in which the body and gate terminals are connected to ground. (c) Small-signal analysis performed directly on the circuit diagram with the T model of (b) used implicitly. (d) Operation with the output open-circuited.
Microelectronic Circuits - Fifth Edition Sedra/Smith

32. sedr42021_0628a.jpg
Figure (a) The output resistance Ro is found by setting vi 5 0. (b) The output resistance Rout is obtained by setting vsig 5 0.
Microelectronic Circuits - Fifth Edition Sedra/Smith

33. sedr42021_0629.jpg
Figure The impedance transformation property of the CG configuration.
Microelectronic Circuits - Fifth Edition Sedra/Smith

34. sedr42021_0630.jpg
Figure Equivalent circuit of the CG amplifier illustrating its application as a current buffer. Rin and Rout are given in Fig. 6.29, and Gis 5 Avo (Rs/Rout) . 1.
Microelectronic Circuits - Fifth Edition Sedra/Smith

35. sedr42021_0631a.jpg
Figure (a) The common-gate amplifier with the transistor internal capacitances shown. A load capacitance CL is also included. (b) Equivalent circuit for the case in which ro is neglected.
Microelectronic Circuits - Fifth Edition Sedra/Smith

36. sedr42021_0632a.jpg Figure 6.32 Circuits for determining Rgs and Rgd.
Microelectronic Circuits - Fifth Edition Sedra/Smith

37. sedr42021_0633a.jpg
Figure (a) Active-loaded common-base amplifier. (b) Small-signal analysis performed directly on the circuit diagram with the BJT T model used implicitly. (c) Small-signal analysis with the output open-circuited.
Microelectronic Circuits - Fifth Edition Sedra/Smith

38. sedr42021_0634.jpg
Figure Analysis of the CB circuit to determine Rout. Observe that the current ix that enters the transistor must equal the sum of the two currents v/rp and v/Re that leave the transistor, that is; ix 5 v/rp 1 v/Re.
Microelectronic Circuits - Fifth Edition Sedra/Smith

39. sedr42021_0635.jpg
Figure Input and output resistances of the CB amplifier.
Microelectronic Circuits - Fifth Edition Sedra/Smith

40. sedr42021_0636a.jpg
Figure (a) The MOS cascode amplifier. (b) The circuit prepared for small-signal analysis with various input and output resistances indicated. (c) The cascode with the output open-circuited.
Microelectronic Circuits - Fifth Edition Sedra/Smith

41. sedr42021_0637ab.jpg
Figure (a and b) Two equivalent circuits for the output of the cascode amplifier. Either circuit can be used to determine the gain Av 5 vo/vi, which is equal to Gv because Rin 5 ¥ and thus vi 5 vsig. (c) Equivalent circuit for determining the voltage gain of the CS stage, Q1.
Microelectronic Circuits - Fifth Edition Sedra/Smith

42. sedr42021_0638.jpg
Figure The cascode circuit with the various transistor capacitances indicated.
Microelectronic Circuits - Fifth Edition Sedra/Smith

43. sedr42021_0639abc.jpg
Figure Effect of cascoding on gain and bandwidth in the case Rsig 5 0. Cascoding can increase the dc gain by the factor A0 while keeping the unity-gain frequency constant. Note that to achieve the high gain, the load resistance must be increased by the factor A0.
Microelectronic Circuits - Fifth Edition Sedra/Smith

44. sedr42021_0640a.jpg
Figure (a) The BJT cascode amplifier. (b) The circuit prepared for small-signal analysis with various input and output resistances indicated. Note that rx is neglected. (c) The cascode with the output open-circuited.
Microelectronic Circuits - Fifth Edition Sedra/Smith

45. sedr42021_0641a.jpg
Figure (a) Equivalent circuit for the cascode amplifier in terms of the open-circuit voltage gain Avo 5 –bA0. (b) Equivalent circuit in terms of the overall short-circuit transconductance Gm . gm. (c) Equivalent circuit for determining the gain of the CE stage, Q1.
Microelectronic Circuits - Fifth Edition Sedra/Smith

46. sedr42021_0642.jpg
Figure Determining the frequency response of the BJT cascode amplifier. Note that in addition to the BJT capacitances Cp and Cm, the capacitance between the collector and the substrate Ccs for each transistor are also included.
Microelectronic Circuits - Fifth Edition Sedra/Smith

47. sedr42021_0643.jpg Figure 6.43 A cascode current-source.
Microelectronic Circuits - Fifth Edition Sedra/Smith

48. sedr42021_0644.jpg Figure 6.44 Double cascoding.
Microelectronic Circuits - Fifth Edition Sedra/Smith

49. sedr42021_0645.jpg Figure 6.45 The folded cascode.
Microelectronic Circuits - Fifth Edition Sedra/Smith

50. sedr42021_0646a.jpg Figure 6.46 BiCMOS cascodes.
Microelectronic Circuits - Fifth Edition Sedra/Smith

51. sedr42021_0647a.jpg
Figure (a) A CS amplifier with a source-degeneration resistance Rs. (b) Circuit for small-signal analysis. (c) Circuit with the output open to determine Avo. (d) Output equivalent circuit. (e) Another output equivalent circuit in terms of Gm.
Microelectronic Circuits - Fifth Edition Sedra/Smith

52. sedr42021_0648a.jpg
Figure (a) The CS amplifier circuit, with a source resistance Rs, prepared for frequency-response analysis. (b) Determining the resistance Rgd seen by the capacitance Cgd.
Microelectronic Circuits - Fifth Edition Sedra/Smith

53. sedr42021_0649a.jpg
Figure A CE amplifier with emitter degeneration: (a) circuit; (b) analysis to determine Rin; and (c) analysis to determine Avo.
Microelectronic Circuits - Fifth Edition Sedra/Smith

54. sedr42021_0650a.jpg
Figure (a) An IC source follower. (b) Small-signal equivalent-circuit model of the source follower. (c) A simplified version of the equivalent circuit. (d) Determining the output resistance of the source follower.
Microelectronic Circuits - Fifth Edition Sedra/Smith

55. sedr42021_0651a.jpg
Figure Analysis of the high-frequency response of the source follower: (a) Equivalent circuit; (b) simplified equivalent circuit; and (c) determining the resistance Rgs seen by Cgs.
Microelectronic Circuits - Fifth Edition Sedra/Smith

56. sedr42021_0652a.jpg
Figure (a) Emitter follower. (b) High-frequency equivalent circuit. (c) Simplified equivalent circuit.
Microelectronic Circuits - Fifth Edition Sedra/Smith

57. sedr42021_0653a.jpg
Figure (a) CD–CS amplifier. (b) CC–CE amplifier. (c) CD–CE amplifier.
Microelectronic Circuits - Fifth Edition Sedra/Smith

58. sedr42021_0654a.jpg
Figure Circuits for Example 6.13: (a) The CC–CE circuit prepared for low-frequency small-signal analysis; (b) the circuit at high frequencies, with Vsig set to zero to enable determination of the open-circuit time constants; and (c) a CE amplifier for comparison.
Microelectronic Circuits - Fifth Edition Sedra/Smith

59. sedr42021_0655a.jpg
Figure (a) The Darlington configuration; (b) voltage follower using the Darlington configuration; and (c) the Darlington follower with a bias current I applied to Q1 to ensure that its b remains high.
Microelectronic Circuits - Fifth Edition Sedra/Smith

60. sedr42021_0656a.jpg
Figure (a) A CC–CB amplifier. (b) Another version of the CC–CB circuit with Q2 implemented using a pnp transistor. (c) The MOSFET version of the circuit in (a).
Microelectronic Circuits - Fifth Edition Sedra/Smith

61. sedr42021_0657a.jpg
Figure (a) Equivalent circuit for the amplifier in Fig. 6.56(a). (b) Simplified equivalent circuit. Note that the equivalent circuits in (a) and (b) also apply to the circuit shown in Fig. 6.56(b). In addition, they can be easily adapted for the MOSFET circuit in Fig. 6.56(c), with 2rp eliminated, Cp replaced with Cgs, Cm replaced with Cgd, and Vp replaced with Vgs.
Microelectronic Circuits - Fifth Edition Sedra/Smith

62. sedr42021_0658.jpg Figure 6.58 A cascode MOS current mirror.
Microelectronic Circuits - Fifth Edition Sedra/Smith

63. sedr42021_0659.jpg
Figure A current mirror with base-current compensation.
Microelectronic Circuits - Fifth Edition Sedra/Smith

64. sedr42021_0660a.jpg
Figure The Wilson bipolar current mirror: (a) circuit showing analysis to determine the current transfer ratio; and (b) determining the output resistance. Note that the current ix that enters Q3 must equal the sum of the currents that leave it, 2i.
Microelectronic Circuits - Fifth Edition Sedra/Smith

65. sedr42021_0661a.jpg
Figure The Wilson MOS mirror: (a) circuit; (b) analysis to determine output resistance; and (c) modified circuit.
Microelectronic Circuits - Fifth Edition Sedra/Smith

66. sedr42021_0662.jpg Figure 6.62 The Widlar current source.
Microelectronic Circuits - Fifth Edition Sedra/Smith

67. sedr42021_0663a.jpg Figure 6.63 Circuits for Example 6.14.
Microelectronic Circuits - Fifth Edition Sedra/Smith

68. sedr42021_0664.jpg
Figure Capture schematic of the CS amplifier in Example 6.15.
Microelectronic Circuits - Fifth Edition Sedra/Smith

69. sedr42021_0665.jpg Figure 6.65 Transistor equivalency.
Microelectronic Circuits - Fifth Edition Sedra/Smith

70. sedr42021_0665a.jpg
Figure (a) Voltage transfer characteristic of the CS amplifier in Example 6.15.
Microelectronic Circuits - Fifth Edition Sedra/Smith

71. sedr42021_0665b.jpg
Figure (Continued) (b) Expanded view of the transfer characteristic in the high-gain region. Also shown are the transfer characteristics where process variations cause the width of transistor M1 to change by +15% and –15% from its nominal value of W1 = 12.5 mm.
Microelectronic Circuits - Fifth Edition Sedra/Smith

72. sedr42021_0667.jpg
Figure Capture schematic of the CS amplifier in Example 6.16.
Microelectronic Circuits - Fifth Edition Sedra/Smith

73. sedr42021_0668.jpg
Figure Frequency response of (a) the CS amplifier and (b) the folded-cascode amplifier in Example 6.16, with Rsig = 100 W and Rsig = 1 mW.
Microelectronic Circuits - Fifth Edition Sedra/Smith

74. sedr42021_0669.jpg
Figure Capture schematic of the folded-cascode amplifier in Example 6.16.
Microelectronic Circuits - Fifth Edition Sedra/Smith

75. sedr42021_p06009a.jpg
Figure P6.9
Microelectronic Circuits - Fifth Edition Sedra/Smith

76. sedr42021_p06025.jpg
Figure P6.25
Microelectronic Circuits - Fifth Edition Sedra/Smith

77. sedr42021_p06026.jpg
Figure P6.26
Microelectronic Circuits - Fifth Edition Sedra/Smith

78. sedr42021_p06028.jpg
Figure P6.28
Microelectronic Circuits - Fifth Edition Sedra/Smith

79. sedr42021_p06033.jpg
Figure P6.33
Microelectronic Circuits - Fifth Edition Sedra/Smith

80. sedr42021_p06034.jpg
Figure P6.34
Microelectronic Circuits - Fifth Edition Sedra/Smith

81. sedr42021_p06035.jpg
Figure P6.35
Microelectronic Circuits - Fifth Edition Sedra/Smith

82. sedr42021_p06037.jpg
Figure P6.37
Microelectronic Circuits - Fifth Edition Sedra/Smith

83. sedr42021_p06046.jpg
Figure P6.46
Microelectronic Circuits - Fifth Edition Sedra/Smith

84. sedr42021_p06054.jpg
Figure P6.54
Microelectronic Circuits - Fifth Edition Sedra/Smith

85. sedr42021_p06057.jpg
Figure P6.57
Microelectronic Circuits - Fifth Edition Sedra/Smith

86. sedr42021_p06061.jpg
Figure P6.61
Microelectronic Circuits - Fifth Edition Sedra/Smith

87. sedr42021_p06063.jpg
Figure P6.63
Microelectronic Circuits - Fifth Edition Sedra/Smith

88. sedr42021_p06065.jpg
Figure P6.65
Microelectronic Circuits - Fifth Edition Sedra/Smith

89. sedr42021_p06072.jpg
Figure P6.72
Microelectronic Circuits - Fifth Edition Sedra/Smith

90. sedr42021_p06073.jpg
Figure P6.73
Microelectronic Circuits - Fifth Edition Sedra/Smith

91. sedr42021_p06075.jpg
Figure P6.75
Microelectronic Circuits - Fifth Edition Sedra/Smith

92. sedr42021_p06076a.jpg
Figure P6.76
Microelectronic Circuits - Fifth Edition Sedra/Smith

93. sedr42021_p06083.jpg
Figure P6.83
Microelectronic Circuits - Fifth Edition Sedra/Smith

94. sedr42021_p06084.jpg
Figure P6.84
Microelectronic Circuits - Fifth Edition Sedra/Smith

95. sedr42021_p06085.jpg
Figure P6.85
Microelectronic Circuits - Fifth Edition Sedra/Smith

96. sedr42021_p06093.jpg
Figure P6.93
Microelectronic Circuits - Fifth Edition Sedra/Smith

97. sedr42021_p06096.jpg
Figure P6.96
Microelectronic Circuits - Fifth Edition Sedra/Smith

98. sedr42021_p06098.jpg
Figure P6.98
Microelectronic Circuits - Fifth Edition Sedra/Smith

99. sedr42021_p06099a.jpg
Figure P6.99
Microelectronic Circuits - Fifth Edition Sedra/Smith

100. sedr42021_p06107a.jpg
Figure P6.107
Microelectronic Circuits - Fifth Edition Sedra/Smith

101. sedr42021_p06122.jpg
Figure P6.121
Microelectronic Circuits - Fifth Edition Sedra/Smith

102. sedr42021_p06123.jpg
Figure P6.122
Microelectronic Circuits - Fifth Edition Sedra/Smith

103. sedr42021_p06124.jpg
Figure P6.123
Microelectronic Circuits - Fifth Edition Sedra/Smith

104. sedr42021_p06125.jpg
Figure P6.124
Microelectronic Circuits - Fifth Edition Sedra/Smith

105. sedr42021_p06128a.jpg
Figure P6.127
Microelectronic Circuits - Fifth Edition Sedra/Smith

106. sedr42021_p06131.jpg
Figure P6.130
Microelectronic Circuits - Fifth Edition Sedra/Smith

107. sedr42021_p06136.jpg
Figure P6.134
Microelectronic Circuits - Fifth Edition Sedra/Smith

108. sedr42021_p06145.jpg
Figure P6.143
Microelectronic Circuits - Fifth Edition Sedra/Smith

109. sedr42021_p06146.jpg
Figure P6.144
Microelectronic Circuits - Fifth Edition Sedra/Smith

110. sedr42021_p06147.jpg
Figure P6.145
Microelectronic Circuits - Fifth Edition Sedra/Smith