What is FRAM Memory: ferroelectric RAM

FRAM, ferroelectric RAM is a form of random access memory that combines speed & non-volatility.

FRAM Memory Tutorial Includes:
What is FRAM memory FRAM operation & technology

Memory types: Memory types & technologies DRAM EEPROM Flash FRAM MRAM Phase change memory SDRAM SRAM

FRAM, ferroelectric RAM, is a form of random access memory that combines the fast read and write access of dynamic RAM, DRAM whilst also providing non-volatile capability.

Ferroelectric RAM is also known as F-RAM or FeRAM, as and it is able to compete with Flash technology in many areas, although there are several advantages and disadvantages to using it.

While the name FRAM or ferroelectric RAM seems to indicate that an iron element exists within the memory this is not actually the case.

Ferroelectric RAM history

The development of FRAM dates back to the early days of semiconductor technology. The idea was first proposed in 1952, but it took many years before the idea started to be developed properly as the technologies required to implement it did not exist.

Some work on the technology was started in the 1980s, and then in the early 1990s a part of NASA undertook work into the technology for detecting UV radiation pulses.

However around 1999 the first devices were produced and since then companies including Ramtron, Fujitsu, Texas Instruments, Samsung, Matsushita, Infineon and other have been using the technology.

FRAM usage

Currently ferroelectric RAM is not as widely used as many of the more established technologies including DRAM and Flash. These technologies have become well entrenched and their use is widespread.

As developers often tend to rely on trusted technologies that are guaranteed to deliver the performance they require, they are often reluctant to use technologies like FRAM that are not guaranteed to deliver. Also issues like memory density that limit the size of memory available have caused them not to be so widely used.

However FRAM technology is now being embedded into chips using CMOS technology to enable MCUs to have their own FRAM memories. This requires fewer stages than the number required for incorporating Flash memory onto MCU chips, thereby providing some significant cost reductions.

Basic ferroelectric RAM, FRAM memory cell

A further advantage, apart from the non-volatile nature of the memory is its very low power consumption which lends itself admirably to use within MCUs where power consumption is often a key issue.

FRAM vs other memory technologies comparison

FRAM has characteristics that mean that it lends itself to many different uses. However it is useful to be able to compare the performance and parameters of FRAM with other established memory technologies.

Comparison of Memory technologies with FRAM
	FRAM	SRAM	EEPROM	Flash
Non-volatile	Yes	No	Yes	Yes
Write endurance	1 million billion (i.e. 10¹⁵)	Unlimited	~500 000	1 000 000
Write speed (for 13 kB)	10ms	<10ms	2s
Average active power (µA/MHz)	80	<60	Up to 10 mA	260
Dynamics bit addressable programmability	Yes	Yes	No	No

FRAM advantages and disadvantages

FRAM has a number of distinct advantages when compared to Flash memory which is its nearest competitor. These need to be balanced against what may be termed its disadvantages when considering its use in any system.

FRAM advantages compared to Flash

Lower power usage
Much larger number of write-erase cycles
Faster write performance

FRAM disadvantages compared to Flash

Lower storage density
Higher cost
Overall capacity limitation

FRAM is able to offer many advantages and can be used in many areas, but as in many cases, the use of FRAM memory is a balance of a number of characteristics and parameters which need to be made for any particular circuit design.