Solution:

What is Programmable Link Process Technologies?

• A process technology is the physical method by which a link is made. Several different process technologies are used for programmable links in PLDs.

Fuse Technology:

• This was the original programmable link technology. It is still used in some SPLDs.

• The fuse is a metal link that connects a row and a column in the interconnection matrix. Before programming, there is a fused connection at each intersection.

• To program a device, the selected fuses are opened by passing a current through them sufficient to “blow” the fuse and break the connection. The intact fuses remain and provide a connection between the rows and columns.

  

• The fuse link is illustrated in Figure. Programmable logic devices that use fuse technology are one-time programmable (OTP).

Antifuse Technology:

• An antifuse programmable link is the opposite of a fuse link. Instead of breaking the connection, a connection is made during programming.

• An antifuse starts out as an open circuit Programmable Logic 155 whereas the fuse starts out as a short circuit.

• Before programming, there are no connections between the rows and columns in the interconnection matrix. An antifuse is basically two conductors separated by an insulator.

• To program a device with antifuse technology, a programmer tool applies a sufficient voltage across selected antifuses to break down the insulation between the two conductive materials, causing the insulator to become a lowresistance link.

• The antifuse link is illustrated in Figure. An antifuse device is also a one-time programmable (OTP) device.

EEPROM Technology:

• Electrically erasable programmable read-only memory technology is similar to EPROM because it also uses a type of floating-gate transistor in E2CMOS cells.

• The difference is that EEPROM can be erased and reprogrammed electrically without the need for UV light or special fixtures. An E2CMOS device can be programmed after being installed on a printed circuit board (PCB), and many can be reprogrammed while operating in a system.

• This is called in-system programming (ISP). Figure can also be used as an example to represent an AND array with EEPROM technology.

Flash Technology:

• Flash technology is based on a single transistor link and is both nonvolatile and reprogrammable. Flash elements are a type of EEPROM but are faster and result in higher density devices than the standard EEPROM link.