Design Technologies

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Put them in series - both must be on to complete the circuit. Put them in parallel - either can be on to complete the circuit.Generate all sorts of Switching Functions.NOT the same as Boolean Functions.... Its.RELAY logic - pin ball machines

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Design Technologies Introduction to VLSI Design Introduction © Steven P. Levitan 1998
Views / Abstractions / Hierarchies Structural Behavioral device Circuit Logic Architectural Physical D.Gajski, Silicon Compilation, Addison Wesley, 1988 Introduction to VLSI Design Introduction © Steven P. Levitan 1998
N-Channel Enhancement mode MOS FET – Four Terminal Device - substrate bias –The “self aligned gate” - key to CMOS Introduction to VLSI Design Introduction © Steven P. Levitan 1998
The MOS Transistor Gate Oxyde Gate Polysilicon Field-Oxyde Source Drain (SiO2) n+ n+ p+ stopper p-substrate Bulk Contact CROSS-SECTION of NMOS Transistor Digital Integrated Circuits Introduction © Prentice Hall 1995
MOS transistors Types and Symbols D D G G S S NMOS Enhancement NMOS Depletion D D G G B S S PMOS Enhancement NMOS with Bulk Contact Digital Integrated Circuits Introduction © Prentice Hall 1995
The Basic Idea… » Voltage on the Gate controls the current through the source/drain path » N-Channel - N-Switches are ON when the Gate is HIGH and OFF when the Gate is LOW » P-Channel - P-Switches are OFF when the Gate is HIGH and ON when the Gate is LOW » (ON == Circuit between Source and Drain) Introduction to VLSI Design Introduction © Steven P. Levitan 1998
Transistors as Switches N Switch D 0 1 G Passes “good zeros” S P Switch D 0 G 1 Passes “good ones” S Introduction to VLSI Design Introduction © Steven P. Levitan 1998
….The Rest of the Story... » Put them in series - both must be on to complete the circuit » Put them in parallel - either can be on to complete the circuit » Generate all sorts of Switching Functions » NOT the same as Boolean Functions.... Its RELAY logic - pin ball machines Introduction to VLSI Design Introduction © Steven P. Levitan 1998
Series Parallel Structures D 1 G S D D D 1 G G 1 S S 1 G S N Channel: on=closed when gate is high Introduction to VLSI Design Introduction © Steven P. Levitan 1998
NMOS Transistors in Series/Parallel Connection Transistors can be thought as a switch controlled by its gate signal NMOS switch closes when switch control input is high A B X Y Y = X if A and B A X B Y = X if A OR B Y NMOS Transistors pass a “strong” 0 but a “weak” 1 Digital Integrated Circuits Introduction © Prentice Hall 1995
Series Parallel Structures(2) D 0 G S D D D 0 G G 0 S S 0 G S P Channel: on=closed when gate is low Introduction to VLSI Design Introduction © Steven P. Levitan 1998
PMOS Transistors in Series/Parallel Connection PMOS switch closes when switch control input is low A B X Y Y = X if A AND B = A + B A X B Y = X if A OR B = AB Y PMOS Transistors pass a “strong” 1 but a “weak” 0 Digital Integrated Circuits Introduction © Prentice Hall 1995
Series Parallel Structures (3) N Switch 0 S 1 G Passes “good zeros” D S D S Passes “good ones” G S’ 0 1 P Switch Open Circuit, High Z Bidirectional Switch Introduction to VLSI Design Introduction © Steven P. Levitan 1998
From Switches to Boolean Functions... q Use the Switching Functions to provide paths to Vdd or GND » Vdd is the source of all Truth (Vdd = = 1) » GND is the source of all Falsehood (GND == 0) Pchannel Nchannel 0 0 1 1 Introduction to VLSI Design Introduction © Steven P. Levitan 1998
The Inverter q True to False / False to True Converter 1/0 0/1 Introduction to VLSI Design Introduction © Steven P. Levitan 1998
…That’s it! q This is Non-Trivial: it defines the basis for the logic abstraction which is essential for all Boolean functions. » Provide a path to VDD for 1 » Provide a path to GND for 0 » For complex functions - provide complex paths Introduction to VLSI Design Introduction © Steven P. Levitan 1998
Four Views Logic Transistor Layout Physical Introduction to VLSI Design Introduction © Steven P. Levitan 1998
Cross-Section of CMOS Technology Digital Integrated Circuits Introduction © Prentice Hall 1995
Magic Layout of Inverter Introduction to VLSI Design Introduction © Steven P. Levitan 1998
Magic “Palette” of Layers Introduction to VLSI Design Introduction © Steven P. Levitan 1998