written 2.4 years ago by |
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.