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Application Specific Integrated Circuits: Introduction Jun-Dong Cho SungKyunKwan Univ. Dept. of ECE, Vada Lab. http://vada.skku.ac.kr 2 Contents Why ASIC? Introduction to System On Chip Design Hardware and Software Co-design Low Power ASIC Designs VLSI Algorithmic Design Automation Lab. 3 Why ASIC - Design productivity grows! Complexity increase 40 % per year Design productivity increase 15 % per year Integration of PCB on single die VLSI Algorithmic Design Automation Lab. 4 Silicon in 2010 Dens s ity Acces Time Die Area: 2.5x2.5 cm (Gbits/cm2) (ns ) Voltage: 0.6 V DRAM 8.5 10 Technology: 0.07 m DRAM (Logic) 2.5 10 SRAM (Cache) 0.3 1.5 Dens ity Max. Ave. Power Clock Rate (Mgates/cm2) (W /cm2) (GHz) Cus tom 25 54 3 Std. Cell 10 27 1.5 Gate Array 5 18 1 k Single-Mas GA 2.5 12.5 0.7 FPGA 0.4 4.5 0.25 VLSI Algorithmic Design Automation Lab. 5 ASIC Principles Value-added ASIC for huge volume opportunities; standard parts for quick time to market applications Economics of Design Fast Prototyping, Low Volume Custom Design, Labor Intensive, High Volume CAD Tools Needed to Achieve the Design Strategies System-level design: Concept to VHDL/C Physical design VHDL/C to silicon, Timing closure (Monterey, Magma, Synopsys, Cadence, Avant!) Design Strategies: Hierarchy; Regularity; Modularity; Locality VLSI Algorithmic Design Automation Lab. 6 ASIC Design Strategies Design is a continuous tradeoff to achieve performance specs with adequate results in all the other parameters. Performance Specs - function, timing, speed, power Size of Die - manufacturing cost Time to Design - engineering cost and schedule Ease of Test Generation & Testability - engineering cost, manufacturing cost, schedule VLSI Algorithmic Design Automation Lab. 7 ASIC Flow VLSI Algorithmic Design Automation Lab. 8 Structured ASIC Designs Hierarchy: Subdivide the design into many levels of sub-modules Regularity: Subdivide to max number of similar sub- modules at each level Modularity: Define sub-modules unambiguously & well defined interfaces Locality: Max local connections, keeping critical paths within module boundaries VLSI Algorithmic Design Automation Lab. 9 ASIC Design Options Programmable Logic Programmable Interconnect Reprogrammable Gate Arrays Sea of Gates & Gate Array Design Standard Cell Design Full Custom Mask Design Symbolic Layout Process Migration - Retargeting Designs VLSI Algorithmic Design Automation Lab. 10 ASIC Design Methodologies Custom Cell-based Prediffused Prewired Density Very High High High Medium - Low Performance Very High High High Medium - Low Flexibility Very High High Medium Low Design time Very Long Short Short Very Short Manufacturing time Medium Medium Short Very Short Cost - low volume Very High High High Low Cost - high volume Low Low Low High VLSI Algorithmic Design Automation Lab. 11 Why SOC? • SOC specs are coming from ICT system engineers rather than RTL descriptions •SOC will bridge the gap b/w s/w and their implementation in novel, energy-efficient silicon architecture. •In SOC design, chips are assembled at IP block level (design reusable) and IP interfaces rather than gate level VLSI Algorithmic Design Automation Lab. 12 Common Fabric for IP Blocks Soft IP blocks are portable, but not as predictable as hard IP. Hard IP blocks are very predictable since a specific physical implementation can be characterized, but are hard to port since are often tied to a specific process. Common fabric is required for both portability and predictability. Wide availability: Cell Based Array, metal programmable architecture that provides the performance of a standard cell and is optimized for synthesis. VLSI Algorithmic Design Automation Lab. 13 Four main applications Set-top box: Mobile multimedia system, base station for the home local-area network. Digital PCTV: concurrent use of TV,3D graphics, and Internet services Set-top box LAN service: Wireless home-networks, multi- user wireless LAN Navigation system: steer and control traffic and/or goods-transportation VLSI Algorithmic Design Automation Lab. 14 PC-Multimedia Applications VLSI Algorithmic Design Automation Lab. 15 Types of System-on-a-Chip Designs VLSI Algorithmic Design Automation Lab. 16 Physical gap Timing closure problem: layout-driven logic and RT-level synthesis Energy efficiency requires locality of computation and storage: match for stream-based data processing of speech,images, and multimedia-system packets. Next generation SOC designers must bridge the architectural gap b/w system specification and energy-efficient IP-based architectures, while CAE vendors and IP providers will bridge the physical gap. VLSI Algorithmic Design Automation Lab. 17 Circular Y-Chart VLSI Algorithmic Design Automation Lab. 18 SOC Co-Design Challenges Current systems are complex and heterogenous Contain many different types of components Half of the chip can be filled with 200 low-power, RISC- like processors (ASIP) interconnected by field- programmable buses, embedded in 20Mbytes of distributed DRAM and flash memory, Another Half: ASIC Computational power will not result from multi-GHz clocking but from parallelism, with below 200 MHz. This will greatly simplify the design for correct timing, testability, and signal integrity. VLSI Algorithmic Design Automation Lab. 19 Bridging the architectural gap One-M gate reconfigurable, one-M gate hardwired logic. 50GIPS for programmable components or 500 GIPS for dedicated hardwares Product reliability: design at a level far above the RT level, with reuse factors in excess of 100 Trade-off: 100MOPs/watt (microprocessor) 100GOPs/watt (hardwired) Reconf. Computing with a large number of computing nodes and a very restricted instruction set (Pleiades) VLSI Algorithmic Design Automation Lab. 20 Why Lower Power Portable systems Technology direction long battery life light weight Reduced voltage/power designs based on mature small form factor high performance IC IC priority list technology, high integration power dissipation to minimize size, cost, power, and speed cost performance VLSI Algorithmic Design Automation Lab. 21 Microprocessor Power Dissipation Power(W) Alpha 21164 Alpha 21264 50 45 P III 500 P II 300 40 35 Alpha21064 200 30 25 P6 166 20 P5 66 15 P-PC604 133 10 i486 DX2 66 P-PC601 50 5 i386 DX 16 i486 DX25 i486 DX4 100 i286 i486 DX 50 P-PC750 400 1980 1985 1990 1995 2000 year VLSI Algorithmic Design Automation Lab. 22 Levels for Low Power Design Hardware-software partitioning, System Power down Algorithm Complexity, Concurrency, Locality, Regularity, Data representation Architecture Parallelism, Pipelining, Signal correlations Instruction set selection, Data rep. Circuit/Logic Sizing, Logic Style, Logic Design Technology Threshold Reduction, Scaling, Advanced packaging SOI Possible Power Savings at Different Design Levels Level of Abstraction Expected Saving Algorithm 10 - 100 times Architecture 10 - 90% Logic Level 20 - 40% Layout Level 10 - 30% Device Level 10 - 30% VLSI Algorithmic Design Automation Lab. 23 Power-hungry Applications Signal Compression: HDTV Standard, ADPCM, Vector Quantization, H.263, 2-D motion estimation, MPEG-2 storage management Digital Communications: Shaping Filters, Equalizers, Viterbi decoders, Reed-Solomon decoders VLSI Algorithmic Design Automation Lab. 24 New Computing Platforms P kCFV 2 SOC power efficiency more than 10GOPs/w Higher On Chip System Integration: COTS: 100W, SOAC:10W (inter-chip capacitive loads, I/O buffers) Speed & Performance: shorter interconnection,fewer drivers,faster devices,more efficient processing artchitectures Mixed signal systems Reuse of IP blocks Multiprocessor, configurable computing Domain-specific, combined memory-logic VLSI Algorithmic Design Automation Lab. 25 Low Power Design Flow I Function System Partitioning and System-Level Level Power Analysis HW/SW Allocation Specification Software Behavioral Functions Description Power-driven Behavioral-Level Processor Behavioral Power Analysis Selection Transformation Power Conscious Behavioral Description Software-Level High-Level RT-Level Software Synthesis and Power Analysis Optimization Power Analysis Optimization To RT-Level Design VLSI Algorithmic Design Automation Lab. 26 Low Power Design Flow II RT-level Description Data-path Controller Logic Synthesis Gate-Level RTL RTL and mapping Power Analysis Library Optimization Gate-level Description Standard cell High-Level Switch-Level Processor Memory Library Synthesis and Power Analysis Optimization Control and Steering Logic RTL Macrocells Switch-level Description VLSI Algorithmic Design Automation Lab. 27 Three Factors affecting Energy – Reducing waste by Hardware Simplification: redundant h/w extraction, Locality of reference,Demand-driven / Data-driven computation,Application-specific processing,Preservation of data correlations, Distributed processing – All in one Approach(SOC): I/O pin and buffer reduction – Voltage Reducible Hardwares 2-D pipelining (systolic arrays) SIMD:Parallel Processing:useful for data w/ parallel structure VLIW: Approach- flexible VLSI Algorithmic Design Automation Lab. 28 IBM’s PowerPC Lower Power Architecture Optimum Supply Voltage through Hardware Parallel, Pipelining ,Parallel instruction execution 603e executes five instruction in parallel (IU, FPU, BPU, LSU, SRU) FPU is pipelined so a multiply-add instruction can be issued every clock cycle Low power 3.3-volt design Use small complex instruction with smaller instruction length IBM’s PowerPC 603e is RISC Superscalar: CPI < 1 603e issues as many as three instructions per cycle Low Power Management 603e provides four software controllable power-saving modes. Copper Processor with SOI IBM’s Blue Logic ASIC :New design reduces of power by a factor of 10 times VLSI Algorithmic Design Automation Lab. 29 Power-Down Techniques ◆ Lowering the voltage along with the clock actually alters the energy- per-operation of the microprocessor, reducing the energy required to perform a fixed amount of work VLSI Algorithmic Design Automation Lab. 30 Implementing Digital Systems VLSI Algorithmic Design Automation Lab. 31 H/W and S/W Co-design VLSI Algorithmic Design Automation Lab. 32 Three Co-Design Approaches IFIP International Conference FORTE/PSTV’98, Nov.’98 N.S. Voros et.al, “Hardware -software co-design of embedded systems using multiple formalisms for application development ” ASIP co-design: starts with an application, builds a specific programmable processor and translates the application into software code. H/w and s/w partitioning includes the instruction set design. H/w s/w synchronous system co-design: s/w processor as a master controller, and a set of h/w accelerators as co-processors. Vulcan,Codes,Tosca,Cosyma H/w s/w for distributed systems: mapping of a set of communication processors onto a set of interconnected processors. Behavioral decomposition, process allocation and communication transformation. Coware(powerful),Siera (reuse),Ptolemy (DSP) VLSI Algorithmic Design Automation Lab. 33 Mixing H/W and S/W Argument: Mixed hardware/ software systems represent the best of both worlds. High performance, flexibility, design reuse, etc. Counterpoint: From a design standpoint, it is the worst of both worlds Simulation: Problems of verification, and test become harder Interface: Too many tools, too many interactions, too much heterogeneity Hardware/ software partitioning is “AI- complete”! VLSI Algorithmic Design Automation Lab. 34 Low power partitioning approach Different HW resources are invoked according to the instruction executed at a specific point in time During the execution of the add op., ALU and register are used, but Multiplier is in idle state. Non-active resources will still consume energy since the according circuit continue to switch Calculate wasting energy Adding application specific core and partial running Whenever one core performing, all the other cores are shut down VLSI Algorithmic Design Automation Lab. 35 ASIP Design Given a set of applications, determine micro architecture of ASIP (i. e., configuration of functional units in datapaths, instruction set) To accurately evaluate performance of processor on a given application need to compile the application program onto the processor datapath and simulate object code. The micro architecture of the processor is a design parameter! VLSI Algorithmic Design Automation Lab. 36 ASIP Design Flow VLSI Algorithmic Design Automation Lab. 37 Cross-Disciplinary nature Software for low power:loop transformation leads to much higher temporal and spatial locality of data. Code size becomes an important objective Software will eventually become a part of the chip Behavior-platform-compiler codesign: codesigned with C++ or JAVA, describing their h/w and s/w implementation. Multidisciplinary system thinking is required for future designs (e.g., Eindhoven Embedded Systems Institute http://www.eesi.tue.nl/english) VLSI Algorithmic Design Automation Lab. 38 VLSI Signal Processing Design Methodology pipelining, parallel processing, retiming, folding, unfolding, look-ahead, relaxed look-ahead, and approximate filtering bit-serial, bit-parallel and digit-serial architectures, carry save architecture redundant and residue systems Viterbi decoder, motion compensation, 2D-filtering, and data transmission systems VLSI Algorithmic Design Automation Lab. 39 Low Power DSP DO-LOOP Dominant VSELP Vocoder : 83.4 % 2D 8x8 DCT : 98.3 % LPC computation : 98.0 % DO-LOOP Power Minimization ==> DSP Power Minimization VSELP : Vector Sum Excited Linear Prediction LPC : Linear Prediction Coding VLSI Algorithmic Design Automation Lab. 40 Deep-Submicron Design Flows Rapid evaluation of complex designs for area and performance Timing convergence via estimated routing parasitics In-place timing repair without resynthesis Shorter design intervals, minimum iterations Block-level design and place and route Localized changes without disturbance Integration of complex projects and design reuse VLSI Algorithmic Design Automation Lab. 41 SOC CAD Companies Avant! www.avanticorp.com Synopsys www.synopsys.com Cadence www.cadence.com Topdown design solutions Duet Tech www.duettech.com www.topdown.com Escalade www.escalade.com Xynetix Design Systems Logic visions www.xynetix.com www.logicvision.com Zuken-Redac www.redac.co.uk Mentor Graphics www.mentor.com Palmchip www.palmchip.com Sonic www.sonicsinc.com Summit Design www.summit- design.com VLSI Algorithmic Design Automation Lab.
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