Programmable logic devices based on SRAM technology, used in high-reliability applications at ground level and high altitudes, are susceptible to single-event errors where alpha and neutron radiation causes loss of configuration data. The loss of the underlying FPGA configuration is called a "firm error", and it will remain until detected and corrected. In contrast, a "soft error" is the transient corruption of a single bit of data. Firm errors can cause system-level functional failure, and are very difficult to prevent and correct.

Neutron and alpha radiation do not have adverse effects on Actel antifuse and flash-based FPGAs. Actel offers extremely reliable FPGAs for many applications, including military, aerospace, industrial control, medical, automotive, networking, and communications.

Key Benefits

• Actel antifuse and flash-based FPGAs are not susceptible to configuration loss due to single-event errors (SEE) caused by alpha or neutron radiation
• No SEE mitigation techniques for configuration upsets are required in Actel FPGAs, reducing overall system cost
• Actel FPGAs maintain system integrity at high altitudes and sea level

An independent organization, iRoC Technologies, conducted both neutron and alpha testing on FPGAs using three different programming technologies, with five different architectures from three major FPGA vendors. The FPGAs were tested until a significant number of failures were observed. Based on these results, the Failures-In-Time (FIT) rates were calculated.

Neutron Radiation Test Results Summary

FPGA	Technology	Equivalent FIT Rates per Device
		Ground-level Applications		Commercial Aviation	Military Aviation
		Sea Level	5,000 ft	30,000 ft	60,000 ft
Actel AX1000 (1 M Gate)	0.15 µm Antifuse	No Failures Detected	No Failures Detected	No Failures Detected	No Failures Detected
Actel APA1000 (1 M Gate)	0.22 µm Flash	No Failures Detected	No Failures Detected	No Failures Detected	No Failures Detected
Actel A3PE600 (600 K Gate)	0.13 µm Flash	No Failures Detected	No Failures Detected	No Failures Detected	No Failures Detected
SRAM FPGA (Vendor 1 – 3 M Gate)	0.15 µm SRAM	1,150 FITs	3,900 FITs	170,000 FITs	540,000 FITs
SRAM FPGA (Vendor 1 – 1 M Gate)	90 nm SRAM	320 FITs	1,100 FITs	47,000 FITs	150,000 FITs
SRAM FPGA (Vendor 2 – 1 M Gate)	0.13 µm SRAM	460 FITs	1,600 FITs	67,000 FITs	220,000 FITs
SRAM FPGA (Vendor 2 – 1 M Gate)	90 nm SRAM	730 FITs	2,500 FITs	108,000 FITs	346,000 FITs
SRAM FPGA (Vendor 2 – 2 M Gate)	90 nm SRAM	1,600 FITs	5,500 FITs	236,000 FITs	751,000 FITs

Alpha Radiation Test Results Summary

FPGA	Technology	Configuration Upsets	Functional Failures	Equivalent FIT Rates (FITs)
				Low-Alpha Mold Compound (0.001 α/cm2-hr)	Standard Mold Compound (0.04 α/cm2-hr)
Actel AX1000 (1 M Gate)	0.15 µm Antifuse	Not Measured *	0	No Failures Detected	No Failures Detected
Actel APA1000 (1 M Gate)	0.22 µm Flash	Not Measured *	0	No Failures Detected	No Failures Detected
SRAM FPGA (Vendor 1 – 3 M Gate)	0.15 µm SRAM	1,040	140	140	5,600
SRAM FPGA (Vendor 1 – 1 M Gate)	90 nm SRAM	940	260	260	10,400
SRAM FPGA (Vendor 2 – 1 M Gate)	0.13 µm SRAM	Could not be measured	100	100	4,000

* Design security features in Actel FPGA solutions prevent configuration read back.

• Detailed Test Results and Reports
• Soft/Firm Errors Glossary
• Articles
• Tip of the Week: Correcting soft errors can't be an afterthought  (Apr 2006)