Jan M. Rabaey The Devices Digital Integrated Circuits © Prentice Hall 1995 Introduction Introduction 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 Digital Integrated Circuits © Prentice Hall 1995 Introduction Introduction The Diode n p p n B A SiO 2 Al A B Al A B Cross-section of pn-junction in an IC process One-dimensional representation diode symbol Digital Integrated Circuits © Prentice Hall 1995 Introduction Introduction Depletion Region hole diffusion electron diffusion p n hole drift electron drift Charge Density Distance x+ - Electrical x Field x Potential V ξ ρ W 2 -W 1 ψ 0 (a) Current flow. (b) Charge density. (c) Electric field. (d) Electrostatic potential. Digital Integrated Circuits © Prentice Hall 1995 Introduction Introduction Diode Current Digital Integrated Circuits © Prentice Hall 1995 Introduction Introduction Models for Manual Analysis V D I D = I S (e V D / φ T – 1) + – V D + – + – V Don I D (a) Ideal diode model (b) First-order diode model Digital Integrated Circuits © Prentice Hall 1995 Introduction Introduction Junction Capacitance Digital Integrated Circuits © Prentice Hall 1995 Introduction Introduction Diode Switching Time V src t = 0 V 1 V 2 V D R src t = T I D Time V D ON OFF ON Space charge Excess charge Digital Integrated Circuits © Prentice Hall 1995 Introduction Introduction Secondary Effects –25.0 –15.0 –5.0 5.0 V D (V) –0.1 I D (A) 0.1 0 0 Avalanche Breakdown Digital Integrated Circuits © Prentice Hall 1995 Introduction Introduction Diode Model I D R S C D + - V D Digital Integrated Circuits © Prentice Hall 1995 Introduction Introduction [...]... 1/(k’(W/L)(Vgs-Vt )) Vds © Steven P Levitan 1998 Transistor in Saturation VGS VDS > VGS - VT G D S n+ Digital Integrated Circuits - VGS - VT Introduction + n+ © Prentice Hall 1995 Saturation: Vgs>Vt & Vgd 0 But: channel is “pinched off” Ids = (k’/ 2 )( W/L)(Vgs-Vt)2... Introduction © Steven P Levitan 1998 Regions of Operation Summary REGION NMOS Vtn = 7v k’ = 80µA/V2 PMOS Vtp = -. 7v k’ = 27mA/V2 Off VgsVtp Ids=0 Linear Vgs>Vtn & Vgd>Vtn VgsVt + S VGS - D G Ids n+ Vgd n+ n-channel Depletion Region Vgs p-substrate R B Positive Charge on Gate: Channel exists, Current Flows since Vds > 0 Ids = k’(W/L )( ( Vgs-Vt)Vds-Vds2/ 2) Introduction... (k’/ 2 )( W/L)(Vgs-Vt)2 Introduction to VLSI Design Ids Introduction Vgs “constant current source” Vds © Steven P Levitan 1998 Current-Voltage Relations Digital Integrated Circuits Introduction © Prentice Hall 1995 I-V Relation VDS = VGS-VT Saturation VGS = 4V 1 0.0 VGS = 3V 1.0 2.0 3.0 VDS (V) VGS = 2V VGS = 1V 4.0 5.0 (a) ID as a function of VD S 0.020 ÷√ID Triode Square Dependence ID (mA) 2 VGS = 5V... Prentice Hall 1995 Transistor: No Voltages Gate Oxyde Gate Source Polysilicon n+ Drain n+ p-substrate Field-Oxyde (SiO 2) p+ stopper Bulk Contact CROSS-SECTION of NMOS Transistor Digital Integrated Circuits Introduction © Prentice Hall 1995 Transistor “Off” VgsVt + S VGS - D G Ids n+ n+ n-channel Vgd Depletion Region Vgs p-substrate R B Positive Charge on Gate: Channel...SPICE Parameters Digital Integrated Circuits Introduction © Prentice Hall 1995 The MOS Transistor Gate Oxyde Gate Source Polysilicon n+ Drain n+ p-substrate Field-Oxyde (SiO 2) p+ stopper Bulk Contact CROSS-SECTION of NMOS Transistor Digital Integrated Circuits Introduction © Prentice Hall 1995 Cross-Section of CMOS Technology Digital Integrated Circuits Introduction © Prentice Hall 1995... 0.743 V » K’ = 19.6 µA/V2 (2 0 vs 8 0) ≈ λ = 0.06 V-1 q PMOS » VTO = -0 .739 V » K’ = 5.4 µA/V2 (5 vs 2 7) ≈ λ = 0.19 V-1 Introduction to VLSI Design Introduction © Steven P Levitan 1998 Dynamic Behavior of MOS Transistor G CGS CGD D S CGB CSB CDB B Digital Integrated Circuits Introduction © Prentice Hall 1995 The Gate Capacitance Digital Integrated Circuits Introduction © Prentice Hall 1995 Average Gate . Introduction Models for Manual Analysis V D I D = I S (e V D / φ T – 1) + – V D + – + – V Don I D (a) Ideal diode model (b) First-order diode model Digital. Density Distance x+ - Electrical x Field x Potential V ξ ρ W 2 -W 1 ψ 0 (a) Current flow. (b) Charge density. (c) Electric field. (d) Electrostatic potential.