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Spartan-II FPGA Family Architecture

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FPGAs are landing where ASICs once did.

Family Extended to 200,000 Gates

You asked for it and we listened! We are proud to announce the latest addition to our popular Spartan-II family: the XC2S200. As high-volume designs grow more complex, the need for higher density, increased memory, and greater I/O count grows as well. For these designs, the XC2S200 fits the bill by featuring up to 200,000 system gates, 14 total RAM blocks, and up to 284 I/Os in three low-cost, high-volume packages: PQ208, FG256, and FG456. With the XC2S200, you'll get 36% more logic cells compared with the XC2S150 and five times the density of the largest Spartan or Spartan-XL device.

The XC2S200 includes all the features that make the Spartan-II solution a winning one:

  • Distributed and Block Memory
  • Four Digital Delay Locked Loops per Device
  • Versatile I/O Interface Technology
  • Full PCI Compliance

Spartan-II Architectural Features

Block Diagram

The Spartan-II family of Field Programmable Gate Arrays (FPGAs) is implemented with a regular, flexible, programmable architecture of Configurable Logic Blocks (CLBs), surrounded by a perimeter of programmable Input/Output Blocks (IOBs), interconnected by a powerful hierarchy of versatile routing resources. The architecture also provides advanced functions such as Block RAM and clock control blocks.

Input/Output Block

The Spartan-II IOB features inputs and outputs that support 16 I/O signaling standards, including LVCMOS, HSTL, SSTL, and GTL. These high-speed inputs and outputs are capable of supporting various state-of-the-art memory and bus interfaces. The three IOB registers function either as edge-triggered D-type flip-flops or as level sensitive latches. Each IOB has a clock signal (CLK) shared by the three registers and independent clock enable (CE) signals for each register. In addition to the CLK and CE control signals, the three registers share a Set/Reset (SR). For each register, this signal can be independently configured as a synchronous Set, a synchronous Reset, an asynchronous Preset, or an asynchronous Clear.

Banking of I/O Standards

Some of the I/O standards require VCCO and/or VREF voltages. These voltages externally are connected to device pins that serve groups of IOBs, called banks. Consequently, restrictions exist about which I/O standards can be combined within a given bank. Eight I/O banks result from separating each edge of the FPGA into two banks. Each bank has multiple VCCO pins, all of which must be connected to the same voltage. This voltage is determined by the output standards in use.

In TQ144 and PQ208 packages, all VCCO pins are bonded together internally, and consequently the same VCCO voltage must be connected to all of them. In the CS144 package, bank pairs that share a side are interconnected internally, permitting four choices for VCCO. In both cases, the VREF pins remain internally connected as eight independent banks.

Logic Cells

The basic building block of the Spartan-II CLB is the logic cell (LC). An LC includes a four-input function generator, carry logic, and a storage element. The output from the function generator in each LC drives both the CLB output and the D input of the flip-flop. Each Spartan-II CLB contains four LCs, organized in two similar slices. In addition to the four basic LCs, the Spartan-II CLB contains logic that combines function generators to provide functions of five or six inputs. Consequently, when estimating the number of system gates provided by a given device, each CLB counts as 4.5 LCs.

Spartan-II function generators are implemented as 4-input look-up tables (LUTs). In addition to operating as a function generator, each LUT can provide a 16 x 1-bit synchronous RAM. Furthermore, the two LUTs within a slice can be combined to create a 16 x 2-bit or 32 x 1-bit synchronous RAM, or a 16x1-bit dual-port synchronous RAM. The Spartan-II LUT can also provide a 16-bit shift register that is ideal for capturing high-speed or burst-mode data. This mode can also be used to store data in applications such as digital signal processing. The storage elements in the Spartan-II slice can be configured either as edge-triggered D-type flip-flops or as level-sensitive latches.

Block RAM

Spartan-II FPGAs incorporate several large Block SelectRAM+ memories. These complement the distributed SelectRAM+ resources that provide shallow RAM structures implemented in CLBs. Block SelectRAM+ memory blocks are organized in columns. All Spartan-II devices contain two such columns, one along each vertical edge. These columns extend the full height of the chip. Each memory block is four CLBs high, and consequently, a Spartan-II device 8 CLBs high will contain 2 memory blocks per column, and a total of 4 blocks.

Delay-Locked Loop

Associated with each global clock input buffer is a fully digital Delay-Locked Loop (DLL) that can eliminate skew between the clock input pad and internal clock input pins throughout the device. Each DLL can drive two global clock networks. The DLL monitors the input clock and the distributed clock, and automatically adjusts a clock delay element. Additional delay is introduced such that clock edges reach internal flip-flops exactly one clock period after they arrive at the input. This closed-loop system effectively eliminates clock-distribution delay by ensuring that clock edges arrive at internal flip-flops in synchronism with clock edges arriving at the input.

Configuration

Configuration is the process by which the FPGA is programmed with the configuration file generated by the Xilinx development system. Spartan-II devices support both serial configuration, using the master/slave serial and JTAG modes, as well as byte-wide configuration employing the slave parallel mode.

Spartan-II Enhances the Spartan Series

 
Spartan-II
Spartan-XL
Spartan
Density 15K-200K gates 5K-40K gates 5K-40K gates
I/O Performance 200 MHz 100 MHz 80 MHz
Architecture Virtex derivative XC4000 derivative XC4000 derivative
Block RAM Yes No No
Distributed RAM Yes Yes Yes
DLL Yes No No
I/O Standards 16 4 4
Core Voltage 2.5 V 3.3 V 5 V
5V Tolerance Yes Yes Yes
Process 0.18/0.22 micron 0.25/0.35 micron 0.35/0.5 micron
Configuration Modes Serial, Parallel, JTAG Serial, Express, JTAG Serial, JTAG
Packages VQ100, TQ/CS144, PQ208, FG256/456 PC84, VQ100, TQ/CS144, PQ208/240, BG256, CS280 PC84, VQ100, TQ144, PQ208/240, BG256

Spartan-II Product Table

Feature XC
2S15
XC
2S30
XC
2S50
XC
2S100
XC
2S150
XC
2S200
Syst. Gates
15,000 30,000 50,000 100,000 150,000 200,000
Logic Cells
432 972 1728 2700 3888 5292
CLBs
96 216 384 600 864 1176
Block RAM (bits)
16K 24K 32K 40K 48K 56K
Max
I/O
86 132 176 196 260 284
Pkgs
VQ100
TQ144
CS144
VQ100
TQ144
CS144
PQ208

TQ144

PQ208
FG256


TQ144

PQ208
FG256
FG456


 

PQ208
FG256
FG456


 

PQ208
FG256
FG456

 

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