What Is Ferroelectric RAM?
Ferroelectric random-access memory (FRAM or FeRAM) is a specialized type of solid state data storage medium for computer applications. It differs from the common RAM used in most personal computers in that it is non-volatile, meaning that it retains the data stored in it when power is turned off to the device, not true of standard dynamic RAM (DRAM). The unique properties of the material of which the FRAM is made gives it a natural ferroelectric state, which means that it has a built-in polarization that lends itself to the semi-permanent storage of data without a need for power. This natural polarization means that FRAM has a low power consumption level over standard DRAM.
The data on a FRAM chip can also be changed by applying an electric field to write new information to it, which gives it some similarity to Flash RAM and programmable memory chips in many types of computerized industrial machines known as electrically erasable programmable read-only memory (EEPROM). The main disadvantages of FRAM are that the storage density for data is considerably less than that of other types of RAM and it is more difficult to produce, as the ferroelectric layer can be easily degraded during silicon chip manufacturing. Since ferroelectic RAM cannot hold a great amount of data and would be expensive to make for applications that require a lot of memory, it is most often used in portable computer-based devices like smart cards tied to security systems to enter buildings and radio frequency identifier (RFID) tags used on consumer products to track inventory.
The material most often used to manufacture ferroelectric RAM as of 2011 is lead zirconate titanate (PZT), though the history of the technology can be traced back to its conception in 1952 and first production near the end of the 1980s. The FRAM chip architecture is built upon a model where a storage capacitor is paired with a signaling transistor to make up one programmable metallization cell. The PZT material in ferrorelectric RAM is what gives it the ability to retain data without access to power. While the architecture is based on the same model as DRAM and both store data as binary strings of ones and zeros, only ferroelectric RAM has phase-change memory, where the data is permanently embedded until an applied electric field erases or overwrites it. In this sense, ferroelectric RAM functions in the same way as flash memory or an EEPROM chip, except that the read-write speed is much faster and can be repeated more times before the FRAM chip begins to fail, and the power consumption level is much lower.
Since ferroelectric RAM can have read-write access rates 30,000 times faster than a standard EEPROM chip, along with the fact that it can last 100,000 times longer and have only 1/200th of the power consumption of EEPROM, it is a type of precursor to racetrack memory. Racetrack memory is a type of non-volatile, universal solid-state memory under design in the US that may eventually replace standard computer hard drives and portable flash memory devices. Once commercialized, it is expected that racetrack memory would have a read-write speed that is 100 times faster than current ferroelectric RAM, or 3,000,000 times faster than a standard hard drive's performance level as of 2011.
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