Download presentation
Presentation is loading. Please wait.
1
Transistors (MOSFETs)
MOS Field-Effect Transistors (MOSFETs) 1
2
sedr42021_0401a.jpg Figure 4.1 Physical structure of the enhancement-type NMOS transistor: (a) perspective view; (b) cross-section. Typically L = 0.1 to 3 mm, W = 0.2 to 100 mm, and the thickness of the oxide layer (tox) is in the range of 2 to 50 nm. Microelectronic Circuits - Fifth Edition Sedra/Smith
3
sedr42021_0402.jpg Figure 4.2 The enhancement-type NMOS transistor with a positive voltage applied to the gate. An n channel is induced at the top of the substrate beneath the gate. Microelectronic Circuits - Fifth Edition Sedra/Smith
4
sedr42021_0403.jpg Figure 4.3 An NMOS transistor with vGS > Vt and with a small vDS applied. The device acts as a resistance whose value is determined by vGS. Specifically, the channel conductance is proportional to vGS – Vt’ and thus iD is proportional to (vGS – Vt) vDS. Note that the depletion region is not shown (for simplicity). Microelectronic Circuits - Fifth Edition Sedra/Smith
5
sedr42021_0404.jpg Figure 4.4 The iD–vDS characteristics of the MOSFET in Fig. 4.3 when the voltage applied between drain and source, vDS, is kept small. The device operates as a linear resistor whose value is controlled by vGS. Microelectronic Circuits - Fifth Edition Sedra/Smith
6
sedr42021_0405.jpg Figure 4.5 Operation of the enhancement NMOS transistor as vDS is increased. The induced channel acquires a tapered shape, and its resistance increases as vDS is increased. Here, vGS is kept constant at a value > Vt. Microelectronic Circuits - Fifth Edition Sedra/Smith
7
sedr42021_0406.jpg Figure 4.6 The drain current iD versus the drain-to-source voltage vDS for an enhancement-type NMOS transistor operated with vGS > Vt. Microelectronic Circuits - Fifth Edition Sedra/Smith
8
sedr42021_0407.jpg Figure 4.7 Increasing vDS causes the channel to acquire a tapered shape. Eventually, as vDS reaches vGS – Vt’ the channel is pinched off at the drain end. Increasing vDS above vGS – Vt has little effect (theoretically, no effect) on the channel’s shape. Microelectronic Circuits - Fifth Edition Sedra/Smith
9
sedr42021_0408.jpg Figure 4.8 Derivation of the iD–vDS characteristic of the NMOS transistor. Microelectronic Circuits - Fifth Edition Sedra/Smith
10
sedr42021_0409.jpg Figure 4.9 Cross-section of a CMOS integrated circuit. Note that the PMOS transistor is formed in a separate n-type region, known as an n well. Another arrangement is also possible in which an n-type body is used and the n device is formed in a p well. Not shown are the connections made to the p-type body and to the n well; the latter functions as the body terminal for the p-channel device. Microelectronic Circuits - Fifth Edition Sedra/Smith
11
sedr42021_0410a.jpg Figure (a) Circuit symbol for the n-channel enhancement-type MOSFET. (b) Modified circuit symbol with an arrowhead on the source terminal to distinguish it from the drain and to indicate device polarity (i.e., n channel). (c) Simplified circuit symbol to be used when the source is connected to the body or when the effect of the body on device operation is unimportant. Microelectronic Circuits - Fifth Edition Sedra/Smith
12
sedr42021_0411a.jpg Figure (a) An n-channel enhancement-type MOSFET with vGS and vDS applied and with the normal directions of current flow indicated. (b) The iD–vDS characteristics for a device with k’n (W/L) = 1.0 mA/V2. Microelectronic Circuits - Fifth Edition Sedra/Smith
13
sedr42021_0412.jpg Figure The iD–vGS characteristic for an enhancement-type NMOS transistor in saturation (Vt = 1 V, k’n W/L = 1.0 mA/V2). Microelectronic Circuits - Fifth Edition Sedra/Smith
14
sedr42021_0413.jpg Figure Large-signal equivalent-circuit model of an n-channel MOSFET operating in the saturation region. Microelectronic Circuits - Fifth Edition Sedra/Smith
15
sedr42021_0414.jpg Figure The relative levels of the terminal voltages of the enhancement NMOS transistor for operation in the triode region and in the saturation region. Microelectronic Circuits - Fifth Edition Sedra/Smith
16
sedr42021_0415.jpg Figure Increasing vDS beyond vDSsat causes the channel pinch-off point to move slightly away from the drain, thus reducing the effective channel length (by DL). Microelectronic Circuits - Fifth Edition Sedra/Smith
17
sedr42021_0416.jpg Figure Effect of vDS on iD in the saturation region. The MOSFET parameter VA depends on the process technology and, for a given process, is proportional to the channel length L. Microelectronic Circuits - Fifth Edition Sedra/Smith
18
sedr42021_0417.jpg Figure Large-signal equivalent circuit model of the n-channel MOSFET in saturation, incorporating the output resistance ro. The output resistance models the linear dependence of iD on vDS and is given by Eq. (4.22). Microelectronic Circuits - Fifth Edition Sedra/Smith
19
sedr42021_0418a.jpg Figure (a) Circuit symbol for the p-channel enhancement-type MOSFET. (b) Modified symbol with an arrowhead on the source lead. (c) Simplified circuit symbol for the case where the source is connected to the body. (d) The MOSFET with voltages applied and the directions of current flow indicated. Note that vGS and vDS are negative and iD flows out of the drain terminal. Microelectronic Circuits - Fifth Edition Sedra/Smith
20
sedr42021_0419.jpg Figure The relative levels of the terminal voltages of the enhancement-type PMOS transistor for operation in the triode region and in the saturation region. Microelectronic Circuits - Fifth Edition Sedra/Smith
21
sedr42021_e0408.jpg Figure E4.8 Microelectronic Circuits - Fifth Edition Sedra/Smith
22
sedr42021_tb0401a.jpg Table 4.1 Microelectronic Circuits - Fifth Edition Sedra/Smith
23
sedr42021_0420.jpg Figure 4.20 Circuit for Example 4.2.
Microelectronic Circuits - Fifth Edition Sedra/Smith
24
sedr42021_0421.jpg Figure 4.21 Circuit for Example 4.3.
Microelectronic Circuits - Fifth Edition Sedra/Smith
25
sedr42021_e0412.jpg Figure E4.12 Microelectronic Circuits - Fifth Edition Sedra/Smith
26
sedr42021_0422.jpg Figure 4.22 Circuit for Example 4.4.
Microelectronic Circuits - Fifth Edition Sedra/Smith
27
sedr42021_0423a.jpg Figure (a) Circuit for Example 4.5. (b) The circuit with some of the analysis details shown. Microelectronic Circuits - Fifth Edition Sedra/Smith
28
sedr42021_0424.jpg Figure 4.24 Circuit for Example 4.6.
Microelectronic Circuits - Fifth Edition Sedra/Smith
29
sedr42021_0425a.jpg Figure 4.25 Circuits for Example 4.7.
Microelectronic Circuits - Fifth Edition Sedra/Smith
30
sedr42021_e0416.jpg Figure E4.16 Microelectronic Circuits - Fifth Edition Sedra/Smith
31
sedr42021_0426a.jpg Figure (a) Basic structure of the common-source amplifier. (b) Graphical construction to determine the transfer characteristic of the amplifier in (a). Microelectronic Circuits - Fifth Edition Sedra/Smith
32
sedr42021_0426c.jpg Figure (Continued) (c) Transfer characteristic showing operation as an amplifier biased at point Q. Microelectronic Circuits - Fifth Edition Sedra/Smith
33
sedr42021_0427.jpg Figure Two load lines and corresponding bias points. Bias point Q1 does not leave sufficient room for positive signal swing at the drain (too close to VDD). Bias point Q2 is too close to the boundary of the triode region and might not allow for sufficient negative signal swing. Microelectronic Circuits - Fifth Edition Sedra/Smith
34
sedr42021_0428a.jpg Figure 4.28 Example 4.8.
Microelectronic Circuits - Fifth Edition Sedra/Smith
35
sedr42021_0428b.jpg Figure 4.28 (Continued)
Microelectronic Circuits - Fifth Edition Sedra/Smith
36
sedr42021_0429.jpg Figure The use of fixed bias (constant VGS) can result in a large variability in the value of ID. Devices 1 and 2 represent extremes among units of the same type. Microelectronic Circuits - Fifth Edition Sedra/Smith
37
sedr42021_0430a.jpg Figure Biasing using a fixed voltage at the gate, VG, and a resistance in the source lead, RS: (a) basic arrangement; (b) reduced variability in ID; (c) practical implementation using a single supply; (d) coupling of a signal source to the gate using a capacitor CC1; (e) practical implementation using two supplies. Microelectronic Circuits - Fifth Edition Sedra/Smith
38
sedr42021_0431.jpg Figure 4.31 Circuit for Example 4.9.
Microelectronic Circuits - Fifth Edition Sedra/Smith
39
sedr42021_0432.jpg Figure Biasing the MOSFET using a large drain-to-gate feedback resistance, RG. Microelectronic Circuits - Fifth Edition Sedra/Smith
40
sedr42021_0433a.jpg Figure (a) Biasing the MOSFET using a constant-current source I. (b) Implementation of the constant-current source I using a current mirror. Microelectronic Circuits - Fifth Edition Sedra/Smith
41
sedr42021_0434.jpg Figure Conceptual circuit utilized to study the operation of the MOSFET as a small-signal amplifier. Microelectronic Circuits - Fifth Edition Sedra/Smith
42
sedr42021_0435.jpg Figure Small-signal operation of the enhancement MOSFET amplifier. Microelectronic Circuits - Fifth Edition Sedra/Smith
43
sedr42021_0436.jpg Figure Total instantaneous voltages vGS and vD for the circuit in Fig Microelectronic Circuits - Fifth Edition Sedra/Smith
44
sedr42021_0437a.jpg Figure Small-signal models for the MOSFET: (a) neglecting the dependence of iD on vDS in saturation (the channel-length modulation effect); and (b) including the effect of channel-length modulation, modeled by output resistance ro = |VA| /ID. Microelectronic Circuits - Fifth Edition Sedra/Smith
45
sedr42021_0438a.jpg Figure Example 4.10: (a) amplifier circuit; (b) equivalent-circuit model. Microelectronic Circuits - Fifth Edition Sedra/Smith
46
sedr42021_0439.jpg Figure Development of the T equivalent-circuit model for the MOSFET. For simplicity, ro has been omitted but can be added between D and S in the T model of (d). Microelectronic Circuits - Fifth Edition Sedra/Smith
47
sedr42021_0440a.jpg Figure (a) The T model of the MOSFET augmented with the drain-to-source resistance ro. (b) An alternative representation of the T model. Microelectronic Circuits - Fifth Edition Sedra/Smith
48
sedr42021_0441a.jpg Figure Small-signal equivalent-circuit model of a MOSFET in which the source is not connected to the body. Microelectronic Circuits - Fifth Edition Sedra/Smith
49
sedr42021_tb0402a.jpg Table 4.2 Microelectronic Circuits - Fifth Edition Sedra/Smith
50
sedr42021_0442.jpg Figure Basic structure of the circuit used to realize single-stage discrete-circuit MOS amplifier configurations. Microelectronic Circuits - Fifth Edition Sedra/Smith
51
sedr42021_e0430a.jpg Figure E4.30 Microelectronic Circuits - Fifth Edition Sedra/Smith
52
sedr42021_tb0403a.jpg Table 4.3 Microelectronic Circuits - Fifth Edition Sedra/Smith
53
sedr42021_0443a.jpg Figure (a) Common-source amplifier based on the circuit of Fig (b) Equivalent circuit of the amplifier for small-signal analysis. (c) Small-signal analysis performed directly on the amplifier circuit with the MOSFET model implicitly utilized. Microelectronic Circuits - Fifth Edition Sedra/Smith
54
sedr42021_0444a.jpg Figure (a) Common-source amplifier with a resistance RS in the source lead. (b) Small-signal equivalent circuit with ro neglected. Microelectronic Circuits - Fifth Edition Sedra/Smith
55
sedr42021_0445a.jpg Figure (a) A common-gate amplifier based on the circuit of Fig (b) A small-signal equivalent circuit of the amplifier in (a). (c) The common-gate amplifier fed with a current-signal input. Microelectronic Circuits - Fifth Edition Sedra/Smith
56
sedr42021_0446a.jpg Figure (a) A common-drain or source-follower amplifier. (b) Small-signal equivalent-circuit model. (c) Small-signal analysis performed directly on the circuit. (d) Circuit for determining the output resistance Rout of the source follower. Microelectronic Circuits - Fifth Edition Sedra/Smith
57
sedr42021_tb0404a.jpg Table 4.4 Microelectronic Circuits - Fifth Edition Sedra/Smith
58
sedr42021_tb0404c.jpg Table 4.4 (Continued)
Microelectronic Circuits - Fifth Edition Sedra/Smith
59
sedr42021_0447a.jpg Figure (a) High-frequency equivalent circuit model for the MOSFET. (b) The equivalent circuit for the case in which the source is connected to the substrate (body). (c) The equivalent circuit model of (b) with Cdb neglected (to simplify analysis). Microelectronic Circuits - Fifth Edition Sedra/Smith
60
sedr42021_0448.jpg Figure Determining the short-circuit current gain Io /Ii. Microelectronic Circuits - Fifth Edition Sedra/Smith
61
sedr42021_tb0405.jpg Table 4.5 Microelectronic Circuits - Fifth Edition Sedra/Smith
62
sedr42021_0449a.jpg Figure (a) Capacitively coupled common-source amplifier. (b) A sketch of the frequency response of the amplifier in (a) delineating the three frequency bands of interest. Microelectronic Circuits - Fifth Edition Sedra/Smith
63
sedr42021_0450a.jpg Figure Determining the high-frequency response of the CS amplifier: (a) equivalent circuit; (b) the circuit of (a) simplified at the input and the output; Microelectronic Circuits - Fifth Edition Sedra/Smith
64
sedr42021_0450c.jpg Figure (Continued) (c) the equivalent circuit with Cgd replaced at the input side with the equivalent capacitance Ceq; (d) the frequency response plot, which is that of a low-pass single-time-constant circuit. Microelectronic Circuits - Fifth Edition Sedra/Smith
65
sedr42021_0451.jpg Figure Analysis of the CS amplifier to determine its low-frequency transfer function. For simplicity, ro is neglected. Microelectronic Circuits - Fifth Edition Sedra/Smith
66
sedr42021_0452.jpg Figure Sketch of the low-frequency magnitude response of a CS amplifier for which the three break frequencies are sufficiently separated for their effects to appear distinct. Microelectronic Circuits - Fifth Edition Sedra/Smith
67
sedr42021_0453.jpg Figure 4.53 The CMOS inverter.
Microelectronic Circuits - Fifth Edition Sedra/Smith
68
sedr42021_0454a.jpg Figure Operation of the CMOS inverter when vI is high: (a) circuit with vI = VDD (logic-1 level, or VOH); (b) graphical construction to determine the operating point; (c) equivalent circuit. Microelectronic Circuits - Fifth Edition Sedra/Smith
69
sedr42021_0455a.jpg Figure Operation of the CMOS inverter when vI is low: (a) circuit with vI = 0 V (logic-0 level, or VOL); (b) graphical construction to determine the operating point; (c) equivalent circuit. Microelectronic Circuits - Fifth Edition Sedra/Smith
70
sedr42021_0456.jpg Figure The voltage transfer characteristic of the CMOS inverter. Microelectronic Circuits - Fifth Edition Sedra/Smith
71
sedr42021_0457a.jpg Figure Dynamic operation of a capacitively loaded CMOS inverter: (a) circuit; (b) input and output waveforms; (c) trajectory of the operating point as the input goes high and C discharges through QN; (d) equivalent circuit during the capacitor discharge. Microelectronic Circuits - Fifth Edition Sedra/Smith
72
sedr42021_0458.jpg Figure The current in the CMOS inverter versus the input voltage. Microelectronic Circuits - Fifth Edition Sedra/Smith
73
sedr42021_0459a.jpg Figure (a) Circuit symbol for the n-channel depletion-type MOSFET. (b) Simplified circuit symbol applicable for the case the substrate (B) is connected to the source (S). Microelectronic Circuits - Fifth Edition Sedra/Smith
74
sedr42021_0460a.jpg Figure The current-voltage characteristics of a depletion-type n-channel MOSFET for which Vt = –4 V and k¢n(W/L) = 2 mA/V2: (a) transistor with current and voltage polarities indicated; (b) the iD–vDS characteristics; (c) the iD–vGS characteristic in saturation. Microelectronic Circuits - Fifth Edition Sedra/Smith
75
sedr42021_0461.jpg Figure The relative levels of terminal voltages of a depletion-type NMOS transistor for operation in the triode and the saturation regions. The case shown is for operation in the enhancement mode (vGS is positive). Microelectronic Circuits - Fifth Edition Sedra/Smith
76
sedr42021_0462.jpg Figure Sketches of the iD–vGS characteristics for MOSFETs of enhancement and depletion types, of both polarities (operating in saturation). Note that the characteristic curves intersect the vGS axis at Vt. Also note that for generality somewhat different values of |Vt| are shown for n-channel and p-channel devices. Microelectronic Circuits - Fifth Edition Sedra/Smith
77
sedr42021_e0451.jpg Figure E4.51 Microelectronic Circuits - Fifth Edition Sedra/Smith
78
sedr42021_e0452.jpg Figure E4.52 Microelectronic Circuits - Fifth Edition Sedra/Smith
79
sedr42021_0463.jpg Figure Capture schematic of the CS amplifier in Example 4.14. Microelectronic Circuits - Fifth Edition Sedra/Smith
80
sedr42021_0464.jpg Figure Frequency response of the CS amplifier in Example 4.14 with CS = 10 mF and CS = 0 (i.e., CS removed). Microelectronic Circuits - Fifth Edition Sedra/Smith
81
sedr42021_p04018a.jpg Figure P4.18 Microelectronic Circuits - Fifth Edition Sedra/Smith
82
sedr42021_p04033a.jpg Figure P4.33 Microelectronic Circuits - Fifth Edition Sedra/Smith
83
sedr42021_p04036.jpg Figure P4.36 Microelectronic Circuits - Fifth Edition Sedra/Smith
84
sedr42021_p04037.jpg Figure P4.37 Microelectronic Circuits - Fifth Edition Sedra/Smith
85
sedr42021_p04038.jpg Figure P4.38 Microelectronic Circuits - Fifth Edition Sedra/Smith
86
sedr42021_p04041.jpg Figure P4.41 Microelectronic Circuits - Fifth Edition Sedra/Smith
87
sedr42021_p04042a.jpg Figure P4.42 Microelectronic Circuits - Fifth Edition Sedra/Smith
88
sedr42021_p04043a.jpg Figure P4.43 Microelectronic Circuits - Fifth Edition Sedra/Smith
89
sedr42021_p04044a.jpg Figure P4.44 Microelectronic Circuits - Fifth Edition Sedra/Smith
90
sedr42021_p04045.jpg Figure P4.45 Microelectronic Circuits - Fifth Edition Sedra/Smith
91
sedr42021_p04046a.jpg Figure P4.46 Microelectronic Circuits - Fifth Edition Sedra/Smith
92
sedr42021_p04047.jpg Figure P4.47 Microelectronic Circuits - Fifth Edition Sedra/Smith
93
sedr42021_p04048.jpg Figure P4.48 Microelectronic Circuits - Fifth Edition Sedra/Smith
94
sedr42021_p04054.jpg Figure P4.54 Microelectronic Circuits - Fifth Edition Sedra/Smith
95
sedr42021_p04061.jpg Figure P4.61 Microelectronic Circuits - Fifth Edition Sedra/Smith
96
sedr42021_p04066.jpg Figure P4.66 Microelectronic Circuits - Fifth Edition Sedra/Smith
97
sedr42021_p04074.jpg Figure P4.74 Microelectronic Circuits - Fifth Edition Sedra/Smith
98
sedr42021_p04075.jpg Figure P4.75 Microelectronic Circuits - Fifth Edition Sedra/Smith
99
sedr42021_p04077.jpg Figure P4.77 Microelectronic Circuits - Fifth Edition Sedra/Smith
100
sedr42021_p04086.jpg Figure P4.86 Microelectronic Circuits - Fifth Edition Sedra/Smith
101
sedr42021_p04087.jpg Figure P4.87 Microelectronic Circuits - Fifth Edition Sedra/Smith
102
sedr42021_p04088a.jpg Figure P4.88 Microelectronic Circuits - Fifth Edition Sedra/Smith
103
sedr42021_p04097.jpg Figure P4.97 Microelectronic Circuits - Fifth Edition Sedra/Smith
104
sedr42021_p04099.jpg Figure P4.99 Microelectronic Circuits - Fifth Edition Sedra/Smith
105
sedr42021_p04101.jpg Figure P4.101 Microelectronic Circuits - Fifth Edition Sedra/Smith
106
sedr42021_p04104.jpg Figure P4.104 Microelectronic Circuits - Fifth Edition Sedra/Smith
107
sedr42021_p04117.jpg Figure P4.117 Microelectronic Circuits - Fifth Edition Sedra/Smith
108
sedr42021_p04120.jpg Figure P4.120 Microelectronic Circuits - Fifth Edition Sedra/Smith
109
sedr42021_p04121a.jpg Figure P4.121 Microelectronic Circuits - Fifth Edition Sedra/Smith
110
sedr42021_p04123.jpg Figure P4.123 Microelectronic Circuits - Fifth Edition Sedra/Smith
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.