What is FRAM ? | Characteristics of FRAM |
What is FRAM ?
FRAM (ferroelectric random access memory) is a non-volatile memory that uses ferroelectric film as a capacitor for storing data. Possessing characteristics of both ROM and RAM devices, FRAM features high speed access, high endurance in write mode, low power consumption, non-volatility, and excellent tamper resistance. It is therefore ideal memory for use in smart cards, which needs high security and low power consumption, as well as cellular phones and other devices.
What is Ferroelectric material?
PZT (Pb (ZrTi)O3) material which has a perovskite-type structure (ABO3), is commonly used as a typical ferroelectric material.
An electric polarization of PZT (shift up/down of Zr/Ti atom) remains after applying and removing an external electric field,
from which a nonvolatile property results. As a result of this, the power consumption required for data storage is very low.
PZT Crystal Structure
Comparison of FRAM® with other memory products
| Memory products | *1 SRAM |
*2 DRAM |
*3 E2PROM |
*4 FLASH |
*5 FRAM |
|---|---|---|---|---|---|
| Memory type | Volatile back-up | Volatile | Non -volatile | Non -volatile | Non -volatile |
| Cell structure | 6T | 1T/1C | 2T | 1T | 1T/1C 2T/2C |
| Read cycle (ns) | 12 | 70 | 200 | 70 | 110 |
| Internal write voltage (V) | 3.3 | 3.3 | 20 (supply voltage 3.3V) | 12 (supply voltage 3.3V) | 3.3 |
| Write cycle | 12ns | 70ns | 3ms | 1 sec. | 110ns |
| Data write | Overwrite | Overwrite | Erase + Write | Erase + Write | Overwrite |
| Data erase | Unnecessary | Unnecessary | Byte (64 byte page) | Sector (8K /16K /32K /64K) | Unnecessary |
| Endurance | ∞ | ∞ | 1E5 | 1E5 | 1E10 to 1E12 |
| Stand-by current (µA) | 7 | 1000 | 20 | 5 | 5 |
| Read operation current (mA) | 40 | 80 | 5 | 12 | 4 |
| Write operation current (mA) | 40 | 80 | 8 | 35 | 4 |
Notes: *1: 512K x 8bit, *2: 2M x 8bit, *3: 8K x 8bit, *4: 1M x 8bit, *5: 8K x 8bit
- FRAM is a registered trademark of Ramtron International Corporation -
Features of FRAM
There are conventional nonvolatile memories since as E2PROM and Flash. However, on the demand of high-speed and low-power consumption and high-rewriting endurance, FRAM has the superior performance as compared with those nonvolatile memories.
Compared with E2PROM, Fujitsu's FRAM has the following features:
1. 1/30,000 high-speed write time
2. 1/400 or less power consumption
3. 100,000 times or more rewrite count capability.
