FRAM(Ferroelectric Random Access Memory) is also known as FeRAM. It is a type of memory that uses a ferroelectric film as a capacitor to store data. FRAM has the characteristcs of both ROM(Read Only Memory) and RAM(Random Access Memory), and advantages in high-speed writing,high endurance, low power consumption and tamper resistance.
The figure below explains PZT crystal structure, which is commonly used as a typical ferroelectric material. There are zirconium and titanium in the lattice, which have two stabilization points. They can move between the points according to the external electric field. Once the position is settled, it will not move anymore even the absence of electric filed. Top and bottom electrodes structure a capacitor. Then, the capacitor plots bottom electrode voltage and polarization, which yields a hysteresis loop. Data is stored in the form of "1" or "0".
* Non-Volatile: even when not powered, the stored information can be retained
FRAM has following advantages over conventional memories;
Table1 is a comparison table for specification differences between FRAM and other memory devices.
|Data rewrite method||Overwrite||Erase+ Write||Sector erase+ Write||Overwrite|
|Write cycle time||150ns*2||5ms||10µs||55ns|
|Endurance||Max. 1012(1 trillion cycles*3)*2||106(1million cycles)||105(100thousand cycles)||Unlimited|
|Write operation current||5mA(Typ.)*2
*1) T=Transistor. C=Capacitor
*2) Specs of 256Kb stand-alone FRAM memory
*3) Total cycles of read and write operation
Fujitsu Semiconductor provides stand-alone memory which has FRAM's advantages including non-volatility, high-speed writing, low power consumption and high endurance. You can use it for various applications such as mobile, OA equipment, digital appliance, banking terminal.
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