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Dr.D.RUKMANIDEVI PPT.ppt
1. FPGA AND ITS LOW POWER
TECHNIQUE
(FIELD PROGRAMMABLE GATE ARRAY)
Presented by :
Dr.D.RUKMANIDEVI
PROFESSOR
R.M.D.ENGINEERING COLLEGE
1
2. HISTORY
Programmable Read Only Memory (PROM)-1970
fuse programming
n- address i/p can implement n i/p logic fun.
Problem:
Area efficiency.
Programmable Logic Array (PLA)-1977
Programmable AND plane followed by
programmable or wired OR plane.
Sum of product form
Problem :
Two level programming adds delay
2
3. NEXT -
Programmable Array Logic (PAL)-1977
Programmable AND plane and fixed OR plane.
Flexible comparably.
All these PLA and PAL are Simple Programmable
Logic Devices (SPLD).
Problem:
Logic plane structure grows rapidly with number of
inputs
3
5. NEXT -
To mitigate the problem
Complex Programmable Logic Devices (CPLD)
programmably interconnect multiple SPLDs.
Problem :
Extending to higher density difficult
Less flexibility
5
7. FPGA -1984
A Field Programmable Gate Array (FPGA) is a
Programmable Logic Device(PLD) with higher densities
and capable of implementing different functions in a short
period of time.
FPGA is an IC with ability to reconfigure its circuitry for a
desired application or function at any time after
manufacturing
Adaptive hardware that continuously changes in response
to the input data or processing environment
Combination of general-purpose processors and ASICs
7
8. You can download FPGAs as many time as you want
no limit - with different functionalities every time if
you want. If you make a mistake in your design, just
fix your "logic function", re-compile and re-
download it. No PCB, solder or component to
change.
The designs can run much faster than if you were to
design a board with discrete components, since
everything runs within the FPGA, on its silicon die.
FPGAs loose their functionality when the power
goes away (like RAM in a computer that looses its
content).
You have to re-download them when power goes
back up to restore the functionality.
8
9. FPGA OVERVIEW
2-D array of logic blocks and flip-flops with
programmable interconnections.
Compact design
User can configure
Intersections between the logic blocks
The function of each block
9
11. WHICH WAY TO GO?
Low development cost
Short time to market
Reprogrammable
High performance
ASICs FPGAs
Low power
Low cost in
high volumes
11
12. OTHER FPGA ADVANTAGES
Manufacturing cycle for ASIC is very costly, lengthy
and engages lots of manpower
Mistakes not detected at design time have large
impact on development time and cost
FPGAs are perfect for rapid prototyping of digital
circuits
Easy upgrades like in case of software
Unique applications
FPGA Weaknesses: cost, density, speed
FPGA Vendors: Xilinx, Altera, Actel, Atmel, Lucent,
Cypress, QuickLogic, IBM, Motorola 12
13. SOME OF THE EXAMPLES OF FPGA USAGE ARE:
Fast prototypes of large designs for simulation/
verification later to be implemented in ICs
Signal, image processing: filters, warping, music
Graphics, UART and other device controllers
Military: target dependent correlation/recognition
Cryptography: DES search
“Hardware” genetic algorithms
13
14. FPGA – A DETAILED LOOK
Based on the principle of functional completeness
FPGA: Functionally complete elements (Logic
Blocks) placed in an interconnect framework
Interconnection framework comprises of wire
segments and switches; Provide a means to
interconnect logic blocks
Circuits are partitioned to logic block size,
mapped and routed
14
15. LOGIC BLOCKS
Purpose: to implement combinational and sequential
logic functions.
Logic blocks can be implemented by:-
• Transistor pairs
• Multiplexers
• Look up tables( LUT)
• Wide fan-in AND-OR structure.
Granularity: is the hardware abstraction level.
According to granularity, two types of Blocks :
Fine Grain Logic Blocks
Coarse Grain Logic Blocks
15
16. FINE GRAIN
1. The Cross Point
FPGA
Transistors are
interconnected.
Logic block is
implemented using
transistor pair tiles.
16
17. 2. Plessey FPGA :-
• 2-input NAND gate forms basic building block
• Static RAM programming technology
17
18. FINE GRAIN
Advantage:
Blocks are fully utilized.
Disadvantage:
Require large numbers of wire segments and
programmable switches.
Need more area.
18
19. COARSE GRAIN LOGIC BLOCKS
Many types exists according to implementations
Multiplexer Based and Look-up-Table Based are most
common
1. The Xilinx Logic Block:
A SRAM function as a LUT.
Address line of SRAM as input
Output of SRAM gives the logic output
k-input logic function =2^k size SRAM
K-i/p LUT gives 2^2^k logic functions
19
25. SPARTAN 3E
Standard Performance -4
High Performance -5
I-Industrial (–40°C to 100°C)
C-Commercial (0°C to 85°C)
Package Type
Plastic Quad Flat Pack
Fine-Pitch Ball Grid Array
25
26. Advantage:
High functionality
k inputs logic block can be implemented in no. of ways
Disadvantage:
Large no of memory cells required if i/p is large
CONFIGURABLE LOGIC BLOCK
26
28. FPGA ROUTING ARCHITECTURE
Island – Style FPGA
Row – Based FPGA
Sea – Gates FPGA
Hierarchical FPGA
Commercial FPGAs can be classified into the
four groups, based on their routing
architecture.
28
33. 2. Altera logic block:-
Wide fan-in
Up to 100 i/p AND gate fed into OR gate with 3-8 i/ps
Advantage:-
Few logic block can implement the entire functionality
Less area required
Disadvantage:-
If i/ps are less, usage density of block will be low
Pull up devices consume static power
33
35. Altera routing methodology
It has two level hierarchy.
first level => 16 or 32 of the logic
blocks are grouped into a Logic Array Block(LAB)
connections are formed using EPROM
Second level=> LABs are interconnected using
Programmable Interconnect Array(PIA)
35
38. Actel routing methodology
more wire segments in horizontal direction.
i/p & o/p vertical tracks can make connection with
every horizontal track.
Routing is flexible.
Drawback:-
more switches are required => more capacitive load.
38
39. PROGRAMMING METHODOLOGY
Electrically programmable switches are used to program
FPGA
Properties of programmable switch determine on-
resistance, parasitic capacitance, volatility,
reprogrammability, size etc.
Various programming techniques are:-
SRAM programming technology
Floating Gate Programming
Antifuse programming methodology
39
40. SRAM programming technology
Use Static RAM cells to control pass gates or multiplexers.
1= closed switch connection
0= open
For mux, SRAM determines the mux input selection
process.
Advantage
• Fast re-programmability
• Standard IC fabrication Tech. is used
Disadvantage
• SRAM volatile
• Requires large area
40
41. Floating gate programming
Tech used in EPROM and
EEPROM devices is used
Switch is disable by applying high
voltage to gate-2 between gate-1
and drain.
The charge is removed by UV light
Advantage:-No external permanent
memory is needed to program it at
power-up
Disadvantage:-
Extra processing steps
Static power loss due to pull up
resistor and high on resistance
41
42. Antifuse programming methodology
2 terminal device with an un programmed state
present very high resistance.
By applying high voltage create a low resistance link.
Advantage:-
Small size
Low series resistance and low parasitic capacitance
42
44. WHY BETTER ?
FPGA programmed using electrically programmable
switches
Routing architectures are complex.
Logic is implemented using multiple levels of lower
fan-in gates.
Shorter time to market
Ability to re-program in the field to fix bugs
FPGA DISADVANTAGE
FPGAs are generally slower than their application-
specific integrated circuit (ASIC)
Can't handle as complex a design, and draw more
power.
44
46. SEMICONDUCTOR INDUSTRY MOVING TO FINFET
The Invention of the Transistor – Electronics Era
Begins
46
In 1947, Bardeen, Brattain, and Shockley invented the
first (bipolar) transistor – awarded the 1956 Nobel
Prize in Physics
~10 YEARS LATER – THE
MODERN MOSFET IS BORN
47. 47
1991-1999: THE FIRST 3D “FINFET” TRANSISTOR-A SELF
ALIGNED DOUBLE GATE MOSFET SCALABLE TO 20NM
48. 48
Allows smaller
junction sizes
3D TRANSISTOR (TRI-GATE AND FINFET) ADVANTAGE SUMMARY
Intel’s 14 nm
Tri-Gate
Technology
Higher Effective
Channel Width
Lower Leakage
Current
And 2nd
Generation
Technology
> 2X Core
Performance
Improved SEU
Resistance
> 50% Power
Reduction
Higher
Densities
Technology
Leadership