1 Digital Circuit Design on FPGA Nattha Jindapetch November 2008.
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Transcript of 1 Digital Circuit Design on FPGA Nattha Jindapetch November 2008.
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Digital Circuit Design on FPGA
Nattha JindapetchNovember 2008
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Agenda
Design trends IC technology revolution Design styles System integration
Programmable logic FPGA design flow & Tools LABs
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IC Technology Revolution
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Invention of the Transistor
1947: first point contact transistor at Bell Labs
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The First Integrated Circuit
1966: ECL 3-Input gate at Motorola
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1970’s processes usually had only nMOS transistors Inexpensive, but consume power while idle
MOS Integrated Circuits
Intel 1101
256-bit SRAM
Intel 4004 4-bit Proc
1000 Trs, 1 MHz operation
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High Performance Processors
2001: Intel Pentium Microprocessor 42 M transistors, 1.5 GHz operation CMOS, Low power
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Moore’s Law
Transistor counts have doubled every 2 years
Integration Levels
SSI: 10 gates
MSI: 1000 gates
LSI: 10,000 gates
VLSI: > 10k gates
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Corollaries
Many other factors grow exponentially Ex: clock frequency, processor performance
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Evolution of a Revolution
www.intel.com
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Design Styles
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Design Styles
Full-custom ASIC Cell-based ASIC Gate array Programmable logic
Field programmable gate array (FPGA)
Programmable logic device (PLD) Complex PLD (CPLD)
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Full-Custom ASIC
layout-based the designer draws ea
ch polygon “by hand” More compact design
but longer design time only for analogue and
high(est) volumes
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Cell-Based ASIC
used predefined building blocks (“cells”)
designer creates a schematic that interconnects these cells
layout = placement & interconnection of cells
for “functionality” or “time-to market” driven design
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Gate Array
Each chip is prefabricated with an array of identical gates or cells.
The chip is “customized” by fabricating routing layers on top.
Time to market, cost
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Field programmable gate array
Chips are prefabricated with logic blocks and interconnects.
Logic and interconnects can be programmed (erased and reprogrammed) by users.
No fabrication is needed. Cost efficient for
medium complexity (< 1M gates) designs
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PLD and CPLD
Programmable Logic Device (PLD, PLA, PAL, ...) AND-OR combinatorial logic, plus FF designer writes Boolean equations Small complexity only
Complex PLD (CPLD) several PLD blocks programmable interconnection matrix
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Trends in Design styles
More complex system Digital and Analog IC (Mixed Signal) Hardware and Software Co-design SoC, SoPC
Resulting in … Higher abstract design level Advanced design tools to automate complex desig
ns Short design time to compete market share
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Why HW/SW Co-design?
Hardware (ASIC, FPGA) Fast But very expensive
Software (Processor) Flexible But slow
Hardware + Software = Good solution? Requirements?
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Example of Digital Camera
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System Integration
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System Integration
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Benefits
Less components Component costs Board size and cost Assembly and testing costs
Less inter-chip interconnects Reliability Power consumption Board design, fabrication and assembly costs
Smaller system volume (in cm2) and weight Higher integration rate Smaller case costs Smaller transport costs
In high volumes (in pcs), also lower circuit costs
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SoP System-on-Package (SoP) or System-in-Pack
age (SiP) are advanced multi-chip packaging technology complementing SoC.
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SoC
System-on-Chip –one term, many definitions “IBM definition”: a single-chip system containing analo
g, digital and MEMS (micro-electro-mechanical system) parts
“Lucent definition”: a single-chip system containing analog and digital parts
“Synopsys definition”: a single-chip digital system SoC, System-on-Chip is a relatively complex standalone s
ystem on a single semiconductor chip containing at least one processor, maybe some analog or even electro-mechanical parts, where the design needs to address on-chip communication
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SoPC System-on-a-Programmable Chip (SOPC) term coi
ned by Synopsys SoPC is a FPGA technology based user programm
able solution P&R and programming done by the user
No delay on prototype production No delay on mass production start No NRE (production start) costs
Production tests done by the IC vendor Design resource and time savings in the design flow Quick and cheap modifications
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SoC vs SoPC SoC manufacturing is costly
Foundries more and more expensive Mask costs for fine-grain lithography are increasing Silicon vendors concentrate on big customers with big quantities Very few multi-project prototype services available Malfunction will cost a lot of money and time Full-wafer prototype round may cost even 500,000 ... 1M €
FPGA-type solutions are also evolving On-chip processor cores Multi-million gate capacity Some vendors also provide coarse-grain reconfigurability FPGA-based SoC-type platforms thus have a growing niche
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Programmable Logic
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Programmable Logic Programmable digital integrated circuit Standard off-the-shelf parts Desired functionality is implemented by configuring on-chip l
ogic blocks and interconnections Advantages (compared to an ASIC):
Low development costs Short development cycle Device can (usually) be reprogrammed
Types of programmable logic: Complex PLDs (CPLD) Field programmable Gate Arrays (FPGA)
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CPLDArchitecture and Examples
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PLD - Sum of Products
A B C
CBACBAf 1
CBABAf 2
AND plane
Programmable AND array followed by fixed fan-in OR gates
Programmable switch or fuse
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PLD - MacrocellCan implement combinational or sequential logic
A B C
Flip-flop
SelectEnable
D Q
Clock
AND plane
MUX
1f
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CPLD Structure
Integration of several PLD blocks with a programmable interconnect on a single chip
PLDBlockPLD
BlockPLD
BlockPLD
Block
Interconnection MatrixInterconnection Matrix
I/O B
lock
I/O B
lock
I/O B
lock
I/O B
lock
PLDBlockPLD
BlockPLD
BlockPLD
BlockI/O
Blo
ck
I/O B
lock
I/O B
lock
I/O B
lock
• • •
Interconnection MatrixInterconnection Matrix
• • •
• • •
• • •
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CPLD Example – Altera MAX7000
EPM7000 Series Block Diagram
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CPLD Example –Altera MAX7000
EPM7000 Series Device Macrocell
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FPGA Architecture
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FPGA - Generic Structure
FPGA building blocks:
Programmable logic blocksImplement combinatorial and sequential logic
Programmable interconnectWires to connect inputs and outputs to logic blocks
Programmable I/O blocks Special logic blocks at the periphery of device for external connections
I/O
I/O
Logic block
Interconnection switches
I/O
I/O
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Other FPGA Building Blocks
Clock distribution Embedded memory blocks Special purpose blocks:
DSP blocks: Hardware multipliers, adders and registers
Embedded microprocessors/microcontrollers
High-speed serial transceivers
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FPGA – Basic Logic Element LUT to implement combinatorial logic Register for sequential circuits Additional logic (not shown):
Carry logic for arithmetic functions Expansion logic for functions requiring more than 4 inputs
LUTLUT
Out
Select
D Q
ABCD
Clock
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Look-Up Tables (LUT)
Look-up table with N-inputs can be used to implement any combinatorial function of N inputs
LUT is programmed with the truth-table
LUTLUT
ABCD
Z
A
B
C
D
Z
Truth-table Gate implementation
LUT implementation
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LUT Implementation
Example: 3-input LUT
Based on multiplexers (pass transistors)
LUT entries stored in configuration memory cells
0/10/1
0/10/1
0/10/1
0/10/1
0/10/1
0/10/1
0/10/1
0/10/1
X1X2
X3
F
Configuration memorycells
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Programmable Interconnect
Interconnect hierarchy (not shown) Fast local interconnect Horizontal and vertical lines of various lengths
LELE
LELE
LELE
LELE
LELE
LELE
Switch
Matrix
Switch
Matrix
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Switch Matrix Operation
6 pass transistors per switch matrix interconnect point
Pass transistors act as programmable switches
Pass transistor gates are driven by configuration memory cells
After ProgrammingBefore
Programming
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Special Features Clock management
PLL,DLL Eliminate clock skew between external clock
input and on-chip clock Low-skew global clock distribution network
Support for various interface standards High-speed serial I/Os Embedded processor cores DSP blocks
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Configuration Storage Elements
Static Random Access Memory (SRAM) each switch is a pass transistor controlled by the state of an
SRAM bit FPGA needs to be configured at power-on
Flash Erasable Programmable ROM (Flash) each switch is a floating-gate transistor that can be turned
off by injecting charge onto its gate. FPGA itself holds the program
reprogrammable, even in-circuit Fusible Links (“Antifuse”)
Forms a forms a low resistance path when electrically programmed
one-time programmable in special programming machine radiation tolerant
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FPGA Vendors & Device Families
Xilinx Virtex-II/Virtex-4: Feature-
packed high-performance SRAM-based FPGA
Spartan 3: low-cost feature reduced version
CoolRunner: CPLDs Altera
Stratix/Stratix-II High-performance SRAM-
based FPGAs Cyclone/Cyclone-II
Low-cost feature reduced version for cost-critical applications
MAX3000/7000 CPLDs MAX-II: Flash-based FPGA
Actel Anti-fuse based
FPGAs Radiation tolerant
Flash-based FPGAs Lattice
Flash-based FPGAs CPLDs (EEPROM)
QuickLogic ViaLink-based
FPGAs
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State of the Art in FPGAs
Xilinx’s top of the line FPGA 65nm process technology
550MHz RAM blocks 6-input LUTs
Serial connectivity Ethernet MACs Rocket I/O serial 6.5 GBps PCI Express endpoint
Enhanced DSP blocks (25x18-bit MAC) 1760 pin BGA with 1200 I/O EasyPath
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FPGA Design Flow
Xilinx Design Flow
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LABs Lab1: Introduction
Quick start Synthesis results
RTL schematic Technology schematic Device utilization summary Timing summary
Simulation Behavioral Post-Place and Route (PAR) Simulation
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References Theerayod Wiangtong, “Design Trends on Digital Syste
m Design”, Lecture note, Electronic Department, Mahanakorn University of Technology, 2004
Fank Mayer, “High-Level IC Design”, Fraunhofer IIS, Erlangen, Germany, 2004
Stefan Haas, “FPGAs”, CERN Technical Training 2005 Xilinx University Program, http://www.xilinx.com/supp
ort/education-home.htm