1. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. C H A P T E R 13 CMOS Digital Logic Circuits

2. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.1 A logic inverter operating from a dc supply V DD.

3. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

4. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.3 Voltage transfer characteristic of an inverter. The VTC is approximated by three straight-line segments. Note the four parameters of the VTC (V OH, V OL, V IL, and V IH ) and their use in determining the noise margins (NM H and NM L ).

5. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

6. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.5 Typical voltage transfer characteristic (VTC) of a logic inverter, illustrating the definition of the critical points.

7. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.6 The VTC of an ideal inverter.

8. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

9. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.8 A more elaborate implementation of the logic inverter utilizing two complementary switches. This is the basis of the CMOS inverter that we shall study in Section 13.2.

10. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

11. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.10 The resistively loaded MOS inverter and its VTC (Example 13.1).

12. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.11 (a) Enhancement-load MOS inverter; (b) load curve; (c) construction to determine VTC; (d) the VTC.

13. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

14. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.13 An inverter fed with the ideal pulse in (a) provides at its output the pulse in (b). Two delay times are defined as indicated.

15. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

16. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.15 Definitions of propagation delays and transition times of the logic inverter.

17. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.16 Digital IC technologies and logic-circuit families.

18. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.17 The CMOS inverter.

19. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

20. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

21. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.20 The voltage-transfer characteristic of the CMOS inverter when Q N and Q P are matched.

22. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

23. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.22 Dynamic operation of a capacitively loaded CMOS inverter: (a) circuit; (b) input and output waveforms; (c) equivalent circuit during the capacitor discharge; (d) trajectory of the operating point as the input goes high and C discharges through Q N.

24. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.23 Equivalent circuits for determining the propagation delays (a) t PHL and (b) t PLH of the inverter.

25. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.24 Circuit for analyzing the propagation delay of the inverter formed by Q 1 and Q 2, which is driving a similar inverter formed by Q 3 and Q 4.

26. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.25 The Miller multiplication of the feedback capacitance C gd1.

27. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.26 The current in the CMOS inverter versus the input voltage.

28. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.27 Representation of a three-input CMOS logic gate. The PUN comprises PMOS transistors, and the PDN comprises NMOS transistors.

29. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.28 Examples of pull-down networks.

30. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.29 Examples of pull-up networks.

31. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.30 Usual and alternative circuit symbols for MOSFETs.

32. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.31 A two-input CMOS NOR gate.

33. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.32 A two-input CMOS NAND gate.

34. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.33 CMOS realization of a complex gate.

35. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.34 Realization of the exclusive-OR (XOR) function: (a) The PUN synthesized directly from the expression in Eq. (13.86). (b) The complete XOR realization utilizing the PUN in (a) and a PDN that is synthesized directly from the expression in Eq. (13.87). Note that two inverters (not shown) are needed to generate the complemented variables. Also note that in this XOR realization, the PDN and the PUN are not dual networks; however, a realization based on dual networks is possible (see Problem 13.47).

36. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.35 Proper transistor sizing for a four-input NOR gate. Note that n and p denote the W/L ratios of Q N and Q P, respectively, of the basic inverter.

37. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.36 Proper transistor sizing for a four-input NAND gate. Note that n and p denote the W/L ratios of Q N and Q P, respectively, of the basic inverter.

38. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.37 Circuit for Example 13.7.

39. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.38 The MOSFET channel length has been reduced by a factor of 2 every about 5 years. This phenomenon, known as Moore’s law is continuing.

40. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

41. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

42. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

43. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

44. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.

45. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.44 The power-supply line in a deep submicron IC has non-zero resistance. The IR drops along the V DD line cause the voltages delivered to various circuits to differ.

46. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure 13.45 The interconnect (wire) between two circuit blocks, A and B, on an IC chip has finite resistance and a capacitance to ground.

47. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Table 13.3 Summary of Important Characteristics of the CMOS Logic Inverter

48. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure P13.29

49. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure P13.56

50. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Figure P13.66