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EE141 © Digital Integrated Circuits 2nd Devices 1 Digital Integrated Circuits A Design Perspective The Devices Jan M. Rabaey Anantha Chandrakasan Borivoje.

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Presentation on theme: "EE141 © Digital Integrated Circuits 2nd Devices 1 Digital Integrated Circuits A Design Perspective The Devices Jan M. Rabaey Anantha Chandrakasan Borivoje."— Presentation transcript:

1 EE141 © Digital Integrated Circuits 2nd Devices 1 Digital Integrated Circuits A Design Perspective The Devices Jan M. Rabaey Anantha Chandrakasan Borivoje Nikolic July 30, 2002

2 EE141 © Digital Integrated Circuits 2nd Devices 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 EE141 © Digital Integrated Circuits 2nd Devices 3 The Diode Mostly occurring as parasitic element in Digital ICs

4 EE141 © Digital Integrated Circuits 2nd Devices 4 Depletion Region

5 EE141 © Digital Integrated Circuits 2nd Devices 5 Diode Current

6 EE141 © Digital Integrated Circuits 2nd Devices 6 Forward Bias Typically avoided in Digital ICs

7 EE141 © Digital Integrated Circuits 2nd Devices 7 Reverse Bias The Dominant Operation Mode

8 EE141 © Digital Integrated Circuits 2nd Devices 8 Models for Manual Analysis

9 EE141 © Digital Integrated Circuits 2nd Devices 9 Junction Capacitance

10 EE141 © Digital Integrated Circuits 2nd Devices 10 What is a Transistor? A Switch! |V GS | An MOS Transistor

11 EE141 © Digital Integrated Circuits 2nd Devices 11 The MOS Transistor Polysilicon Aluminum

12 EE141 © Digital Integrated Circuits 2nd Devices 12 MOS Transistors - Types and Symbols D S G D S G G S DD S G NMOS Enhancement NMOS PMOS Depletion Enhancement B NMOS with Bulk Contact

13 EE141 © Digital Integrated Circuits 2nd Devices 13 Threshold Voltage: Concept

14 EE141 © Digital Integrated Circuits 2nd Devices 14 The Threshold Voltage

15 EE141 © Digital Integrated Circuits 2nd Devices 15 The Body Effect

16 EE141 © Digital Integrated Circuits 2nd Devices 16 Transistor in Linear

17 EE141 © Digital Integrated Circuits 2nd Devices 17 Transistor in Saturation Pinch-off

18 EE141 © Digital Integrated Circuits 2nd Devices 18 A model for manual analysis

19 EE141 © Digital Integrated Circuits 2nd Devices 19 Current-Voltage Relations A good ol’ transistor Quadratic Relationship 00.511.522.5 0 1 2 3 4 5 6 x 10 -4 V DS (V) I D (A) VGS= 2.5 V VGS= 2.0 V VGS= 1.5 V VGS= 1.0 V ResistiveSaturation V DS = V GS - V T

20 EE141 © Digital Integrated Circuits 2nd Devices 20 Process Data

21 EE141 © Digital Integrated Circuits 2nd Devices 21 Current-Voltage Relations The Deep-Submicron Era Linear Relationship -4 V DS (V) 00.511.522.5 0 0.5 1 1.5 2 2.5 x 10 I D (A) VGS= 2.5 V VGS= 2.0 V VGS= 1.5 V VGS= 1.0 V Early Saturation

22 EE141 © Digital Integrated Circuits 2nd Devices 22 Velocity Saturation  (V/µm)  c = 1.5  n ( m / s )  sat = 10 5 Constant mobility (slope = µ) Constant velocity

23 EE141 © Digital Integrated Circuits 2nd Devices 23 Velocity Saturation (Computation)

24 EE141 © Digital Integrated Circuits 2nd Devices 24 Perspective I D Long-channel device Short-channel device V DS V DSAT V GS - V T V GS = V DD

25 EE141 © Digital Integrated Circuits 2nd Devices 25 I D versus V DS -4 V DS (V) 00.511.522.5 0 0.5 1 1.5 2 2.5 x 10 I D (A) VGS= 2.5 V VGS= 2.0 V VGS= 1.5 V VGS= 1.0 V 00.511.522.5 0 1 2 3 4 5 6 x 10 -4 V DS (V) I D (A) VGS= 2.5 V VGS= 2.0 V VGS= 1.5 V VGS= 1.0 V ResistiveSaturation V DS = V GS - V T Long ChannelShort Channel

26 EE141 © Digital Integrated Circuits 2nd Devices 26 A unified model for manual analysis S D G B

27 EE141 © Digital Integrated Circuits 2nd Devices 27 Transistor Model for Manual Analysis

28 EE141 © Digital Integrated Circuits 2nd Devices 28 The Sub-Micron MOS Transistor  Threshold Variations  Subthreshold Conduction  Parasitic Resistances

29 EE141 © Digital Integrated Circuits 2nd Devices 29 Threshold Variations V T L Long-channel threshold LowV DS threshold Threshold as a function of the length (for lowV DS ) Drain-induced barrier lowering (for lowL) V DS V T

30 EE141 © Digital Integrated Circuits 2nd Devices 30 The MOS Transistor Polysilicon Aluminum

31 EE141 © Digital Integrated Circuits 2nd Devices 31 MOSFET Capacitance Model

32 EE141 © Digital Integrated Circuits 2nd Devices 32 MOSFET Gate Capacitance

33 EE141 © Digital Integrated Circuits 2nd Devices 33 MOSFET DB and SB Capacitance

34 EE141 © Digital Integrated Circuits 2nd Devices 34 Junction Capacitance

35 EE141 © Digital Integrated Circuits 2nd Devices 35 More Process Data

36 EE141 © Digital Integrated Circuits 2nd Devices 36 Problems (2)

37 EE141 © Digital Integrated Circuits 2nd Devices 37 Problems (3)

38 EE141 © Digital Integrated Circuits 2nd Devices 38 Problems (8)

39 EE141 © Digital Integrated Circuits 2nd Devices 39 Problems (17)

40 EE141 © Digital Integrated Circuits 2nd Devices 40 Latch-up


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