F-RAM

F-RAM

(1) (Ferromagnetic RAM) A non-volatile memory that records bits on a magnetic surface. See MRAM.

(2) (Ferroelectric RAM) A non-volatile, random access memory technology from Ramtron International Corporation, Colorado Springs, CO (www.ramtron.com). With product shipping since 1993, F-RAM was the first commercial non-volatile RAM on the market using standard CMOS fabrication. It was initially designed as a high-performance alternative to EEPROM memory with write speed that is orders of magnitude faster and virtually unlimited write cycles. Having the attributes of RAM and the non-volatility of flash, F-RAM may eventually replace flash, DRAM and SRAM.

Polarization in a Crystal
F-RAM uses a ferroelectric capacitor composed of a crystal made up of lead and oxygen atoms plus zirconium or titanium. The crystal has two stable states. When an electric field is applied, the zirconium or titanium atom changes position. The read circuit detects the polarity of the atom as a difference in voltage, which determines the 0 or 1.

The ferroelectric name was chosen because the hysteresis characteristic of the capacitor's charge is similar to ferromagnetic materials. It is somewhat misleading because the capacitor is not made of iron (ferrous), and it is not influenced by magnetic fields. See future memory chips.

The Perovskite Crystal

Ferroelectric capacitors use perovskite crystals, which are found in certain rocks. Named after Russian mineralogist L. A. Perovski, the red dot in the middle is the titanium or zirconium atom, which changes its position. (Image courtesy of Ramtron International Corporation, www.ramtron.com)

Easy Integration

Providing the fastest non-volatile memory in this microcontroller (MCU), a small amount of F-RAM is integrated on this chip with SRAM and flash memory, input/output and processing circuits. (Image courtesy of Ramtron International Corporation, www.ramtron.com)

Just A Few Bits

These Ramtron chips provide non-volatile storage of two or four F-RAM bits in order to maintain the state of a single switch or relay (top) or an LED (bottom). When power is turned back on, these "Nonvolatile State Saver" ICs provide the last known state. (Image courtesy of Ramtron International Corporation, www.ramtron.com)