Chapter 0. Design of ASIC and SoCsoc.yonsei.ac.kr/class/material/logic/CH0.pdf · ¾Cores replacing...
Transcript of Chapter 0. Design of ASIC and SoCsoc.yonsei.ac.kr/class/material/logic/CH0.pdf · ¾Cores replacing...
Chapter 0. Design of ASIC and SoC
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ASIC Design
◈ASIC Design Flow
Design entry and analysis
Technology optimization
Design verification
Layout
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ASIC Design Flow
Front-End
Methodology Verification & Sign-off
Layout & Physical Verification
Key Milestones
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Design Views
◈ HDL views
Technology independent
◈ Netlist views
Technology dependent
◈ Physical views
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ASIC Design Flow
Front-End
Methodology Verification & Sign-off
Layout & Physical Verification
Key Milestones
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Design Entry and Analysis
◈Two principal design description methods
HDL (used for > 50K gates) : VHDL / Verilog
Schematic capture (small design, less often used)
◈Design analysis
Simulation : to make sure the function is correct
HDL simulators
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Design Simulation
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ASIC Design Flow
Front-End
Methodology Verification & Sign-off
Layout & Physical Verification
Key Milestones
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Logic Synthesis
Netlist Description
(Verilog, VHDL, EDIF)
HDLDescription(Verilog or
VHDL)
Design Constraints
(Timing, Power, Area)
Logic Synthesis
ASIC Vendor Synthesis
Library
TechnologyIndependent
Input
TechnologyDependent
Output
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Test Insertion
◈Inserts structures into design to enable a complete and efficient manufacturing test
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Clock Planning
◈Impossible to use an ideal clock to drive all latches
Routability
Circuit drive strength
Clock latency and skew
◈Clock planning inserts the clock network (Clock tree / repowering tree)
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Clock Planning
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ASIC Design Flow
Front-End
Methodology Verification & Sign-off
Layout & Physical Verification
Key Milestones
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Functional Verification
◈Gate level simulation
Make sure the function is not altered or corrupted by the synthesis process
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Formal Verification
◈Achieves the same purpose as gate level simulation
◈Approach is different:
Breaks a design down into a set of Boolean/logic expression
Check the Boolean/logic equivalence
Comparison is exhaustive and fast than simulation
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Formal Verification
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Timing Verification
◈Timing closure : to determine if the design meets the performance target
◈Static timing analysis predicts the timing behavior of a hardware design before manufacture and test
◈It seeks to verify that a signal leaving a storage elements (SE) or primary input (PI) arrives in time and can be latched at next SE or primary output (PO)
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Power Estimation
◈Verify the power consumption based on the gate level netlist
◈Spreadsheet method
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ASIC Design Flow
Front-End
Methodology Verification & Sign-off
Layout & Physical Verification
Key Milestones
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Layout – Routing
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Layout (Physical Design)
◈Placement & Routing
Determine the position and interconnect of each circuits on a die
◈Back-annotation
Extracting timing information from layout for static timing analysis
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Layout (Physical Design)
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SoC (System-on-Chip)
◈Emergence of Very large transistor counts on a single chip
◈Mixed technologies on the same chip
◈Logic, Analog, Memory, ProcessorCreation of Intellectual Property (IP)
◈Reusable core-based designCores replacing standard parts, such as DSP, DRAM, MCU, Flash, and FPGA
◈Today’s chip is tomorrow’s core
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SoC (System-on-Chip)
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SoC Design Trend
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SoC Design Trend
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Benefits of Using SoC
◈Reduced size
◈Reduced overall system cost
◈Lower power consumption
◈Increased performance
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SoC Design Flow
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SoC Co-Design Flow
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IP Core types
◈Hard Core(Technology dependent layout)
Predictable area and performance
Lack flexibility
◈Soft Core(RTL)
leave much of the implementation to the designer
Flexible and process-independent
◈Firm Core(Netlist)
◈Each type of core has different modeling and test requirements
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DFT (Design-For-Testability)
◈Design and Test become closer
Design Test
Design Test
DesignTest
DesignTest
Pre 90’
Early 90’
Mid 90’
Late 90’
IncreasingIntegration
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DFT (Design-For-Testability)
◈ The test process is to provide a measure of the quality of a semiconductor product
◈ DFT is to place the hardware to enable the ability to conduct the quality measurement
◈ Test logic may be addedTo increase the test coverageTo reduce the time it takes to qualify the partTo reduce the cost-of-test
◈ AdvantagesHaving the ability to measure the quality level deterministicallyMaking it easier to generate the necessary vectorsAllowing the cost of test to be reduced in all environments
◈ DisadvantagesNegative impacts on chip design (power, area, timing, pin)It adds tasks and risk to the design scheduleIt adds work and complication to the design methodology flow
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SoC Test
RF/AnalogCore
User Defined
Core
User DefinedCore
DRAM
IP
ROM
IP
IP
UDL
BIST Mem BIST Test AccessSoC Test Controller
IO P
ad
IO P
ad
Low costexternal ATE
• Memory test algorithm• Memory BIST, BISR
• Testable design
• Analog Fault modeling• Mixed signal Built-In Self Test
• Built-In Self Calibration
• Testable core design• Logic BIST• Test reuse• Hierarchical testing
• Core access architecture• Parallel access & bypass• Core isolation
• IP-system test interface
• Test spec.• Test hardware
control• Test
scheduling
• Automatic test pattern • Fault simulation• Testability measure• Scan insertion & synthesis• BIST circuit synthesis• Boundary scan insertion & synthesis
Test Automation
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Scan Testing
◈ Scan is a test methodology that allows one to control and observe all internal nodes in a synchronous design
◈ Application for finite state machines◈ Combinational and sequential elements tested separately
logic Test◈ Two mode operation◈ Normal mode◈ Test mode◈ Advantage
Structured design is possibleCan use combinational ATPGSignificant reduction of test generation timeHigh fault coverage, typically 99.5 Ease of fault diagnosis
◈ DisadvantageAdditional circuitry is added to FFPerformance penaltyTest time increaseNeed to store Patterns : Motivation for BISTInability to test circuits at full speed
Combinational logic
Q D
C
Q D
C
Q D
C
POPI
Clk
MUX0
MUX
MUX0
0
1
1
1
N/T
Sin
Sout
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BIST (Built-In Self-Test)
◈ Capability of a product to carry out an explicit test of itself
Test patterns are generated on-chip
Responses to the test patterns are also evaluated on chip
External operations are required only to initialized the built-in tests and to check the test results (go/no-go)
◈ Advantage
No need for expensive tester
At-speed testing
Thorough test
◈ Disadvantages
Initial Design Investment
Area overhead
Pin overhead
Not effective for random testing resistive circuits
Aliasing problem
CUT
Scan ChainLFSR SignatureReg.
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Boundary Scan
◈ Improve testability by reducing the requirements placedon the physical test equipment
◈ Also calledJTAG (Joint Test Action Group) Boundary Scan StandardsIEEE P1149.1
◈ Why use it?Testing interconnections among chipsTesting each chipSnapshot observation of normal system data
◈ Why testing boards?To test board is easier than totest systems
◈ Board Test PhilosophyAs a sorting processAs a repair driverAs a process monitor
SO
core
Bypass
Instruction RegisterSI
TAP