FRAM reaches highest capacity to date
( 01 Oct 2007 )
by Michael Hollabaugh, Senior VP of Marketing and Sales, Ramtron International Corp.
Bridging the gap between the traditional mainstream semiconductor memory technologies of volatile RAM and non-volatile ROM, ferroelectric random access memory (FRAM) is continuing to grow in popularity among design engineers as the nonvolatile memory of choice. Following Ramtron’s recent commercial manufacturing agreement with Texas Instruments and the implementation of FRAM technology on TI’s proven advanced 130 nanometer CMOS manufacturing process, FRAM has surpassed the 1-megabit capacity limit, quadrupling its density to 4-megabits in a standalone memory device (FM22L16) that is already sampling. Full production quantities are planned for later this year and Ramtron is already developing follow-on products that are currently under test.
FRAM memory combines the fast access and low-power qualities of volatile RAM with the ability to retain data without power. Other non-volatile memories such as EEPROM and Flash are less efficient to embed because of multiple mask steps, longer write times, and increased power required to write data. FRAM also consumes much lower power than MRAM and is already commercially proven in demanding automotive, metering, industrial and computing applications.
More specifically, four distinct factors account for FRAM’s continued rise in popularity.
Firstly, unlike other non-volatile memories based on floating gate technology with long write delays, FRAM writes at bus speed. This means it performs write operations at the same speed as read operations, so no delays are needed for the write data to become non-volatile. This compares to a typical EEPROM, where a write operation can take 10 milliseconds to be effective after the data is written to the input buffer. Furthermore, there is no erase operation with FRAM since there is no preferred or default state. So, as with other RAM technologies such as SRAM, data is written without regard to the previous state.
Secondly, FRAM effectively offers unlimited write endurance. It doesn’t wear out like other non-volatile memory types. Floating gate devices, for example, stop retaining data when they have been erased too many times. This is a hard failure mechanism. A fatigued memory cell can no longer store the programmed state. FRAM does not exhibit this type of wear out.
Thirdly, FRAM operates without a charge pump, enabling low power consumption. Floating gate technologies require a high voltage to program a new state, which means that write operations consume considerably more power than read operations. In comparison, FRAM writes at the process core voltage, be it 5 volts, 3 volts or lower on more advanced processes.
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