Where a DRAM uses a dielectric layer to create a non volatile, Random Access Memory, FRAM uses a ferroelectric layer to achieve the same. Also regarded as F-RAM or FeRAM, a ferroelectric memory is similar to flash memory although it is considered to be a better option for a multitude of reasons, the first being its significantly lower power consumption. It is also much more impressive in terms of performance, maximum read/write endurance, as well as better data retention.
FRAM IP Core, as mentioned before, is a non volatile form of memory that utilizes the property of reversible electric polarization in dielectric crystals to produce what seems to be an unlimited amount of read/write cycles. The ferroelectric effect can be seen in metals that are usually known as Perovskites, metals having a peculiar crystalline structure with an atom placed in the center which has two low energy states. When an energy field is applied to this structure, the atom attains a particular direction leading to its polarisation. Depending on the voltage applied, the polarisation can be changed. This change in the states of the ferroelectric material due to application of a voltage allows us to use it as a capacitor in a memory cell.
When writing on FRAM, you utilize a concept similar to what works with DRAM- applying a force field on the ferroelectric material and allowing the atoms to attain either an up or down direction or orientation depending on the voltage applied and the polarity of the charge. This makes the cell achieve either a 1 or a 0 state. Upon reorientation, the atoms holding a 1 charge release a pulse. This process tends to overwrite the cell since the FRAM operates on a destructive process. Ultimately, the cell will have to be rewritten.
While the use of flash and DRAM memories is much more commonplace, the use of FRAM is quickly becoming quite relevant thanks to the benefits it provides. The number one advantage of using FRAM in MCUs as opposed to flash memory is the fact that it costs much less due to the lesser number of steps involved in the incorporation process. It does, however, have lower storage density and can be limited when it comes to the overall capacity. Efforts are being made to improve the density of FRAM arrays and cover all bases to increase the market share and use of FRAM technology. This is being done by making significant improvements in the FRAM foundry process technology as well as cell structures. One of the ideas is to introduce a vertical capacitor structure similar to DRAM in order to reduce the area of the cell footprint.
