FPGA families overview

Field Programmable Gate Array (FPGA) is a type of hardware/logic programmable integrated circuit. It’s flexibility, speed and the increasing number of IP cores make it into a popular solution in embedded system.

The selection of the FPGA core is important when designing a FPGA system. FPGA vendors divide their products into few groups. Each group targets different application such as high performance, mid-range, low cost and low power application. Furthermore, each product group can divide into few families. Every family have different features to support the target applications.

The parameters listed below are important when selecting a FPGA core for a system.,

- Logic Cells/Elements
- Block RAM
- Hard IP block (eg. memory controller and DSP block)
- I/O Pin
- I/O logic level
- Configuration method
- Power consumption
- Cost
- Avaibility
- Supported tools

Since the architecture of logic cells, block ram and DSP block architecture is different between families. Therefore the comparison are not straight forward. The synthesis tool and the logic block architecture may vary the number of logic elements that used by a design.

Most FPGA vendors don’t specify the total power consumption of each devices since it depends on the system design, frequency, and core voltage that used by the system. However, FPGA vendors offer power calculator/estimator that can roughly calculate the power consumption.

Price may vary with different distributer. It is difficult to conclude that which family provides the higher performance-price ratio. If the price is important, then try to contact local distributer to quote the price.

Some of the FPGA vendors and their families are listed below. All parameters are based on the maximum value from each family.

Xilinx
The company offers three SRAM based FPGA families that cover high performance, mid-range and low cost application. Xilinx also offers some special grade FPGAs like space grade, defence grade and automotive grade FPGA. Some of the family are listed here.

Virtex – Xilinx’s high performance FPGA. It offers highest logic cells capacity that enabled by stacked silicon interconnect (SSI). The family targets for ASIC prototyping and high performance communication systems.

Spartan – Low cost FPGA. The family targets for high volume logic designs, consumer-oriented DSP designs, and cost-sensitive embedded applications . Xilinx announce the Spartan 6 series is the end of the series and has been succeed by two families – Kintex and Artix.

Kintex – Mid-range mixed signal FPGA. Optimized for highest performance-price ratio. The family targets for high performance signal processing, long term wireless network and 3D flat panel display.

Artix – Low cost mixed signal FPGA. Optimized for lowest cost and power with small form factor packaging for the highest volume applications. The family targets for medical devices, handheld devices and automation applications.

Feature	Spartan 6	Artix 7	Kintex 7	Virtex 7
Type	SRAM based	SRAM based	SRAM based	SRAM based
Logic Cells	147K	360K	478K	1,955K
Block RAM	4.8Mbit	19Mbit	34Mbit	68Mbit
Configurable ADC	-	17 channels	16 channels	-
DSP slices	180	1,040	1,920	3,600
IO Pins	576	600	500	1,200
PCI-e	x1 Gen1, Endpoint only	x4 Gen2, Root & Endpoint	x8 Gen2, Root & Endpoint	x8 Gen3, Root & Endpoint
Configuration	JTAG, Master SPI, Master BPI, Master/Slave Serial, Master/Slave SelectMAP	JTAG, Master SPI, Master BPI, Master/Slave Serial, Master/Slave SelectMAP	JTAG, Master SPI, Master BPI, Master/Slave Serial, Master/Slave SelectMAP	JTAG, Master SPI, Master BPI, Master/Slave Serial, Master/Slave SelectMAP
Configuration bits (x)	3Mbit<x<33Mbit	haven’t release	23Mbit<x<143Mbit	107Mbit<x<427Mbit

To synthesis a design for Xilinx’s FPGA, Xilinx offers a software pack called ISE design suite to simplify the development cycle. A free edition – ISE webpack is also available but only support limited device.

Altera
Similar to Xilinx, Altera offers three FPGA groups that cover high performance, mid-range and low cost application. They also supports wide temperature range for commercial, industrial, extended industrial, automotive, and military application. Three major family are listed below.

Stratix – Altera’s high performance FPGA family. It targets for high performance communication systems and ASIC prototyping.

Arria – The family targets for cost sensitive applications that require high performance computation functionality, such as digital signal processing (DSP), wireless, wireline and video end markets. Latest series also intergrates an Dual-core ARM Cortex-A9 in the same die.

Cyclone – The family targets for high-volume applications at the lowest cost and lowest power (compares to Stratix and Arria), such application are industrial automation, wireless, wireline, consumers and automotive.

Feature	Cyclone V	Arria V	Stratix V
Type	SRAM based	SRAM based	SRAM based
Logic Cells	301K	504.14K	952K
Block RAM	11.6Mbit	24.14Mbit	52Mbit
DSP Block	342	1,156	704
Users IO	488	704	840
PCI-e	x4 Gen2 Root and Endpoint	x8 Gen2 Root and Endpoint	x8 Gen3 Root and Endpoint
Configuration	JTAG, Active Serial, Passive Serial, Fast Passive Parallel, PCIe	JTAG, Active Serial, Passive Serial, Fast Passive Parallel, PCIe, Internal Hard Processor System	JTAG, Active Serial, Passive Serial, Fast Passive Parallel, PCIe, Partial Reconfiguration
Configuration bits (x)	20Mbit<x<190Mbit (some of the devices haven’t release)	66Mbit<x<177Mbit	89Mbit<x<370Mbit

Altera offers a software development suite called Quartus II to simplify the development cycle. A free web edition is available but only support limited device.

Lattice Semiconductor
Lattice also focuses on SRAM based FPGA. The company offers three major FPGA groups, they are high-value, high performance and non-volatile FPGA. Lattice also offer a very low power FPGA which is known as mobileFPGA, a series of FPGA that acquires from SiliconBlue.

SC – Lattice’s high performance FPGA. It delivers best in class solutions for high throughput standards like Ethernet, PCI Express, SPI4.2 and high speed memory controllers.

ECP – High-value FPGA. It’s target applications are wireline, wireless communication and video processing.

XP – SRAM based FPGA with internal flash memory. The architecture simplify the board level design since no external configuration flash memory is needed.

iCE – This family is known as mobileFPGA. It focuses on the applications that require low power, less space and less bill of materials, such as smartphones and tablets.

Feature	iCE40	XP2	ECP4	SC
Type	SRAM based (with internal non-volatile memory)	SRAM based (with internal non-volatile memory)	SRAM based	SRAM based
Logic Cells	16K	40K	241K	115.2K
Block RAM	384Kbit	885Kbit	10.62Mbit	7.8Mbit
DSP Block	-	8	576	-
Users IO	222	540	512	942
Configuration	Master/Slave SPI (ISP or Socket Adapter)	JTAG, Master/Slave SPI	JTAG, Master/Slave SPI, I2C, Parallel (8bit or 16bit bus)	JTAG, Master SPI, Master/Slave SPI, Master/Slave Parallel, MPI -8 -16 -32
Configuration bits (x)	120Kbit<x<2114Kbit	1.27Mbit<x<8.03Mbit	10.7Mbit<x<54.5Mbit<	4.6Mbit<x<35.8Mbit

Lattice also offers software design suite called Lattice Diamond. A free license is available but with limited device support.

Microsemi (formally Actel)
MicroSemi focuses on Flash based and one time programmable FPGA. The company splits their products into four major groups, they are low power, mixed signal, radiation tolerant and Anti-Fuse FPGA. Each group can further divides into few families. Few of the families are listed below.

IGLOO – Low power FPGA with integrated flash memory. It targets for portable, display and human machine interface application.

SmartFusion – Mixed signal FPGA. Come with hard 32-bit ARM Cortex-M3 microcontroller core, programmable analog with analog-to-digital converter (ADC), voltage/current/temperature monitors, digital-to-analog converter (DAC), comparators, and analog compute engine (ACE).

RT ProASIC – Re-programmable radiation tolerant FPGA. It targets for military and aerospace appications.

Axcelerator – High speed Anti-Fuse FPGA. It targets for consumer, industrial, medical, military and aerospace applications.

Feature	IGLOO	SmartFusion	RT ProASIC3	Axcelerator
Type	Flash Based	Flash Based	Flash Based	One Time Programmable
Logic Cells	75,264	11,520	75,264	10,752(Register) 21,504(Combinatorial)
Block RAM	504Kbit	108Kbit + 64MByte from ARM	444.9Kbit	294.9Kbit
Users IO	620	128	620	684
FlashROM bit	1024	512KByte (using ARM’s flash memory)	1000	- (Anti-Fuse)
Programming	JTAG	JTAG	JTAG	JTAG

MicroSemi also offers a software called Libero that integrates all the nesessary tools for FPGA. Free editions are available, but not all functions are supported. Although the numbers of logic cells are lesser than previous companies. However, the attracting points of these families are the power consumption and non-volatile logic cells.

Some families from four major FPGA vendors are listed above. The numbers from each table are for reference only. Please refer to the datasheet for the exact parameters.

Here are some suggestions for FPGA selection:

Using the vendor specific synthesis tool to synthesize the design. This should get the number of logic elements that used by the family.

Using the vendor specific power estimator roughly calculate the power consumption. Is that over the maximum capability of power supply?

Choosing the FPGA that meets your peripherals’ I/O count and logic level. More I/Os mean more power consumption and cost.

Choosing the FPGA that meets your design’s RAM size.

SRAM based, Flash based or Anti-Fuse FPGA. Difference type will result in different board level design/layout.

Contact your local distributer for price quotation if the cost is sensitive.

Check if any supporting design tools are available for the FPGA.

When the family/device will become obsolescence. Find the latest product may prolong the life cycle of end product.

Other constrains like form factor, temperature and radiation tolerant are important for some applications. Consider them if they are needed.