By John McHale
Industry experts still debate the field programmable gate array (FPGA) vs. custom application specific integrated circuit (ASIC) argument, but designers of both devices agree that flexibility and power efficiency drive current mixed-signal designs.
That argument will probably always exist, says Ken O’Neil, director of military marketing for FPGA designer Actel Corp. in San Jose, Calif. The only difference between now and 20 years ago is that FPGA gate count and power efficiency have tremendously increased, he adds.
Power efficiency and flexibility are key attributes of the company’s first mixed-signal line of FPGAs –called Fusion, O’Neil continues. The device combines mixed-signal analog, flash memory, and programmable logic fabric in a monolithic device. It meets small-size requests by putting functionality on one chip, O’Neil says.
It takes functions such as non-volatile flash memory and real-time clocks and puts them on the chip, O’Neil says. This is what systems integrators want –reliability with less power in a smaller space, he adds.
Systems integrators also are not required to use “the non-volatile memory to load the device configuration at every power up, which gives them much greater flexibility in their designs, and reduces costs too,” O’Neil says.
Actel offers the Fusion FPGA to military, industrial, and medical systems integrators who do not require the FPGA to be radiation-hardened or meet the MIL-STD 883 Class B specification for extreme environments, O’Neil says.
“We are currently evaluating and temperature testing devices to possibly meet MIL-STD 883B or rad-tolerant specifications,” but Actel has no definite time table on when a product will be released, O’Neil says
In military applications, Fusion has found a place in MicroTCA (Micro Telecommunications Computing Architecture) designs due to its power management capability, O’Neil continues. “In medical applications, Fusion is used in high-end surgical equipment,” he adds.
O’Neil referenced a web cast, titled “Actel Fusion in MicroTCA and System Management,” on the Actel Web site that details how Fusion works in MicroTCA applications. According to the web cast, the Fusion FPGA was used as a power-management module enabling a “50 percent reduction in part count, cost, and board space over a typical power module.”
According to the webcast, the Fusion’s hardwired analog-to-digital conversion controls and interfaces also reduced overhead in the MicroTCA module, enabling improved processor performance.
Fusion can be used with the Actel soft MCU core as well as the performance-maximized 32-bit ARM Cortex-M1 and CoreMP7 cores, according to the Actel product Web site.
The device has as much as 8 megabits of user flash memory and “clocking resources such as crystal oscillator circuits and a real-time counter,” O’Neil says. According to the product family data sheet, the memory supports 100 MHz operation and data bus widths of 8, 16, and 32 bits. The flash memory also uses error correction circuitry (ECC) with single-bit error-fix and two-bit error-detect capabilities to improve reliability.
Mid- to low-volume systems integrators also find the Fusion and other FPGAs attractive because they are more cost effective than the traditional ASIC, O’Neil says. They do not have the risk of non-recurring expenses or schedule changes that face ASICs, he continues. Sometimes when a design change is needed for an ASIC it can disrupt the fabrication facility’s production schedule, adding more time and money to the design process, O’Neil explains.
Aeroflex Microelectronic Solutions officials in Colorado Springs, Colo., say the cost effectiveness and power management of their custom mixed-signal ASICs is what wins contracts in rad-hard military satellite applications.
The demand for rad-hard custom mixed-signal ASICs is strong in military and medical applications, says David Kerwin, director of mixed-signal products for Aeroflex Microelectronic Solutions. In the medical industry, Aeroflex’s rad-hard mixed-signal IC designs are used in x-ray systems, he adds.
On the military side, Aeroflex’s mixed-signal business is growing as more and more systems integrators realize it is more cost effective in the long run to invest in a custom ASIC than to put commercial off-the-shelf ICs in a hybrid package or upscreen them for space applications, Kerwin says.
The mixed-signal IC trend today is for cost-effective, reliable, low power devices that fit into small footprints for satellites and avionics systems, Kerwin says.
Hybrid packages and multichip modules can be costly because they go obsolete in three years or less and the associated life cycle expense can be prohibitive, Kerwin continues. Aeroflex accomplishes low-power on a single chip, he adds.
Kerwin declined to go into specifics but says his team is creating a solution for a customer that replaces a four-chip hybrid with a single 512-channel readout ASIC –while reducing its size and power.
Aeroflex designs mixed-signal ASICs in .6-, 0.35-, and 25-micron CMOS as well as 180-, 130-, and 90-nanometer CMOS for military, space, security, medical, and industrial applications. The company’s rad-hard mixed-signal ASIC product line combines high-density, high-speed digital logic with analog and mixed-signal functions on the same monolithic die for precision-data-conversion products. The rad-hard designs are based on Aeroflex’s commercial technology, Kerwin adds.
The devices are radiation-hardened to withstand total-dose radiation ranging from 100 kilorads to 1 megarad. The company also offers FPGA-to-ASIC conversions for rad-hard applications.
