Transcript FPGA Routing Architecture

FPGA and CADs
Presented by Peng Du & Xiaojun Bao
INRTODUCTION
The History of Programmable Logic
Virtex-II Platform FPGA
from Xilinx
•Highest Density FPGAs in The
Industry
•Up to XC2V8000 (8 million systems
gates, 104,832LCs)
•Up to 1108 user I/O’s in the most
advance package offering (FG1152,
and FG1517
FPGA Programming Technologies

SRAM Programming Technology
Anti-fuse
Programming Technology
Erasable
Programming Technology
FPGA Architecture
All FPGAs are composed of three
fundamental components:
Logic
I/O
blocks
blocks
Programmable
routing
A Generic FPGA
I/O block
Logic
block
Programmable
routing
FPGA Logic Block Architecture
The logic block used in an FPGA strongly
influences the FPGA speed and area-efficiency.
While many different logic blocks have been used
in FPGAs, most current commercial FPGAs use
logic blocks based on:
Look-up Table (LUTs)
Structure of LUT
Use Different Input LUTs to Implement
A Boolean Function
Number of Blocks and Block Area
800
Number of
Blocks
50
700
30
600
500
10
2
3
4
5
Number of inputs
6
7
Block
Area
Structure of Cluster-based Logic Block
FPGA Routing Architecture
Commercial FPGAs can be classified into the four
groups, based on their routing architecture.
Island – Style FPGA
 Row – Based FPGA
 Sea – Gates FPGA
 Hierarchical FPGA

The Four Classes of FPGA
An Island – Based FPGA
Example channel segmentation distribution
SRAM Programming Technology
Advantages and Disadvantages of
SRAM Programming
The major advantage of this technology is
that FPGA can be reconfigured (in-circuit)
very quickly and can be produced using a
standard CMOS process technology.
 The chip area required by SRAM approach
is relatively large.

Anti-fuse Programming Technology
An anti-fused normally presents a high-impedance
state but can be “fused” into a low-impedance state
when programmed by a high voltage. The anti-fuse
used in each of FPGAs from different company
differs in construction . But their function is the
same.
Actel anti-fuse – PLICE
Quicklogic anti-fuse - ViaLink
Advantages and Disadvantages of
Anti-fuse Programming
Anti-fuses chip area are small and Antifuses have a significantly lower on
resistance and parasitic capacitance than
transistors, reducing RC delays in the
routing.
 The major disadvantages of anti-fuses is
that their manufacture requires
modifications to the basic CMOS process.

Introduction
This technology is the same as that used in
EPROM and EEPROM memories.
EPROM programming Technology
Advantages and Disadvantages of
EPROM and EEPROM Programming
The major advantage of EPROM is that it
requires re-programmable but do not require
external storage. EEPROM can be reprogrammed in-circuit.
 A disadvantage of EPROM is that the
resistor consumes static power. And
EEPROM requires more chip area and
multiple voltage sources.
