Ferroelectric Random Access Memory

(storage)(FRAM) A type of non-volatile read/write random access semiconductor memory. FRAM combines the advantagesof SRAM - writing is roughly as fast as reading, and EPROM- non-volatility and in-circuit programmability. Current (Feb1997) disadvantages are high cost and low density, but thatmay change in the future. Density is currently at most 32KBon a chip, compared with 512KB for SRAM, 1MB for EPROM and 8MBfor DRAM.

A ferroelectric memory cell consists of a ferroelectriccapacitor and a MOS transistor. Its construction issimilar to the storage cell of a DRAM. The difference is inthe dielectric properties of the material between thecapacitor's electrodes. This material has a high dielectricconstant and can be polarized by an electric field. Thepolarisation remains until it gets reversed by an oppositeelectrical field. This makes the memory non-volatile. Notethat ferroelectric material, despite its name, does notnecessarily contain iron. The most well-known ferroelectricsubstance is BaTiO3, which does not contain iron.

Data is read by applying an electric field to the capacitor.If this switches the cell into the opposite state (flippingover the electrical dipoles in the ferroelectric material)then more charge is moved than if the cell was not flipped.This can be detected and amplified by sense amplifiers.Reading destroys the contents of a cell which must thereforebe written back after a read. This is similar to theprecharge operation in DRAM, though it only needs to be doneafter a read rather than periodically as with DRAM refresh.In fact it is most like the operation of ferrite core memory.

FRAM has similar applications to EEPROM, but can be writtenmuch faster. The simplicity of the memory cell promises highdensity devices which can compete with DRAM.

RAMTRON is the company behind FRAM.

单词	ferroelectric random access memory
释义	Ferroelectric Random Access Memory Ferroelectric Random Access Memory (storage)(FRAM) A type of non-volatile read/write random access semiconductor memory. FRAM combines the advantagesof SRAM - writing is roughly as fast as reading, and EPROM- non-volatility and in-circuit programmability. Current (Feb1997) disadvantages are high cost and low density, but thatmay change in the future. Density is currently at most 32KBon a chip, compared with 512KB for SRAM, 1MB for EPROM and 8MBfor DRAM. A ferroelectric memory cell consists of a ferroelectriccapacitor and a MOS transistor. Its construction issimilar to the storage cell of a DRAM. The difference is inthe dielectric properties of the material between thecapacitor's electrodes. This material has a high dielectricconstant and can be polarized by an electric field. Thepolarisation remains until it gets reversed by an oppositeelectrical field. This makes the memory non-volatile. Notethat ferroelectric material, despite its name, does notnecessarily contain iron. The most well-known ferroelectricsubstance is BaTiO3, which does not contain iron. Data is read by applying an electric field to the capacitor.If this switches the cell into the opposite state (flippingover the electrical dipoles in the ferroelectric material)then more charge is moved than if the cell was not flipped.This can be detected and amplified by sense amplifiers.Reading destroys the contents of a cell which must thereforebe written back after a read. This is similar to theprecharge operation in DRAM, though it only needs to be doneafter a read rather than periodically as with DRAM refresh.In fact it is most like the operation of ferrite core memory. FRAM has similar applications to EEPROM, but can be writtenmuch faster. The simplicity of the memory cell promises highdensity devices which can compete with DRAM. RAMTRON is the company behind FRAM.
随便看	theorem proving system theorems theoretic theoretical theoretical account theoretical aerobic dive limit sato imo sato-imo satoimo satom sat on sat on hands satop satops satori satori alternatives to managing aggression satorp satoy satp satpaev, kanysh satpaev, kanysh imantaevich satpg satphone satpmr sat po