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Digital Integrated Circuits A Design Perspective

Digital Integrated Circuits A Design Perspective. Jan M. Rabaey Anantha Chandrakasan Borivoje Nikolic. The Devices. July 30, 2002. Goal of this chapter. Present intuitive understanding of device operation Introduction of basic device equations Introduction of models for manual analysis

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Digital Integrated Circuits A Design Perspective

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  1. Digital Integrated CircuitsA Design Perspective Jan M. Rabaey Anantha Chandrakasan Borivoje Nikolic The Devices July 30, 2002

  2. Goal of this chapter • Present intuitive understanding of device operation • Introduction of basic device equations • Introduction of models for manual analysis • Introduction of models for SPICE simulation • Analysis of secondary and deep-sub-micron effects • Future trends

  3. B A Al SiO 2 p n Cross-section of pn -junction in an IC process A Al A p n B B One-dimensional representation diode symbol The Diode Mostly occurring as parasitic element in Digital ICs

  4. Depletion Region

  5. Diode Current

  6. Forward Bias Typically avoided in Digital ICs

  7. Reverse Bias The Dominant Operation Mode

  8. Models for Manual Analysis

  9. Junction Capacitance

  10. |V | GS A Switch! An MOS Transistor What is a Transistor?

  11. The MOS Transistor Polysilicon Aluminum

  12. MOS Transistors -Types and Symbols D D G G S S Depletion NMOS Enhancement NMOS D D G G B S S NMOS with PMOS Enhancement Bulk Contact

  13. Threshold Voltage: Concept

  14. The Threshold Voltage

  15. The Body Effect

  16. Transistor in Linear

  17. Pinch-off Transistor in Saturation

  18. A model for manual analysis

  19. -4 x 10 6 VGS= 2.5 V 5 Resistive Saturation 4 VGS= 2.0 V Quadratic Relationship (A) 3 VDS = VGS - VT D I 2 VGS= 1.5 V 1 VGS= 1.0 V 0 0 0.5 1 1.5 2 2.5 V (V) DS Current-Voltage RelationsA good ol’ transistor

  20. Process Data

  21. -4 x 10 2.5 VGS= 2.5 V Early Saturation 2 VGS= 2.0 V 1.5 Linear Relationship (A) D I VGS= 1.5 V 1 VGS= 1.0 V 0.5 0 0 0.5 1 1.5 2 2.5 V (V) DS Current-Voltage RelationsThe Deep-Submicron Era

  22. 5 u = 10 sat ) s / m ( n u x = 1.5 x (V/µm) c Velocity Saturation Constant velocity Constant mobility (slope = µ)

  23. Velocity Saturation (Computation)

  24. Perspective I D Long-channel device V = V GS DD Short-channel device V V - V V DSAT GS T DS

  25. -4 -4 x 10 x 10 2.5 6 VGS= 2.5 V VGS= 2.5 V 5 2 Resistive Saturation VGS= 2.0 V 4 VGS= 2.0 V 1.5 (A) (A) 3 D D VDS = VGS - VT I I VGS= 1.5 V 1 2 VGS= 1.5 V VGS= 1.0 V 0.5 1 VGS= 1.0 V 0 0 0 0.5 1 1.5 2 2.5 0 0.5 1 1.5 2 2.5 V (V) V (V) DS DS ID versus VDS Long Channel Short Channel

  26. G S D B A unified modelfor manual analysis

  27. Transistor Model for Manual Analysis

  28. The Sub-Micron MOS Transistor • Threshold Variations • Subthreshold Conduction • Parasitic Resistances

  29. V V T T Threshold Variations Low V threshold Long-channel threshold DS VDS L Threshold as a function of Drain-induced barrier lowering the length (for low V ) (for low L ) DS

  30. The MOS Transistor Polysilicon Aluminum

  31. MOSFET Capacitance Model

  32. MOSFET Gate Capacitance

  33. MOSFET DB and SB Capacitance

  34. Junction Capacitance

  35. More Process Data

  36. Problems (2)

  37. Problems (3)

  38. Problems (8)

  39. Problems (17)

  40. Latch-up

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