Tezzaron's 3T-iRAM™ memory technology, based on the time-tested DRAM model, offers DRAM-like advantages in cost and density; however, its novel current-sensing process achieves SRAM-like performance.  The name "3T-iRAM" comes from the three-transistor cell design plus the letter "i" -- the engineering symbol for electric current -- to represent the current-sensing technology employed.

3T-iRAM Speed

The dramatic speed of 3T-iRAM was achieved by re-designing the DRAM read mechanism to react to changes in current rather than changes in voltage. In memory circuits, the current changes more quickly than the voltage does, so changes in current can be detected more quickly than changes in voltage. By exploiting this difference, 3T-iRAM technology can provide better-than-SRAM speed at a much lower cost.

3T-iRAM chips incorporate another speed advantage. In many memory devices, some idle time is required in “turnaround” – that is, when a read command is followed by a write command, or vice versa, the memory “bus” is idle for one or more cycles. 3T-iRAM chips require no idle time at all on turnaround; this contributes to their speed.

3T-iRAM Density

3T-iRAM provides twice the capacity of standard SRAM in exactly the same footprint. The reason for this is simple: standard SRAM technology requires six transistors for each memory cell, but each 3T-iRAM cell needs only three transistors.

3t-iRAM Soft Error Resistance

Because 3T-iRAM is built on DRAM technology, it shares DRAM’s reliability; like DRAM, it is more resistant to soft errors than SRAM.

Future Generations of 3T-iRAM

Stacking

Some 3T-iRAM products will be built in a stacked configuration using Tezzaron's patented FaStack® technology. FaStack’s revolutionary design and circuitry will give these stacked parts greater reliability and much higher densities than monolithic 3T-iRAM parts, but at somewhat lower speeds.

Smaller Geometries

Future 3T-iRAM generations will be built with a silicon process that allows smaller features, improving speed and density in both the original monolithic design and in the stacked products.

Multi-Bit Cells

Because 3T-iRAM senses current rather than voltage, very precise measurements are possible.  In fact, current can be measured with a precision six orders of magnitude greater than is possible with voltage. This raises the possibility of multi-bit cells – storing several bits in each cell at widely separated values, as is presently done with high-density Flash chips. 3T-iRAM’s multi-bit cell design adds a capacitor to each three-transistor cell, but because the capacitor can overlap the transistors, it does not greatly increase the cell area. Each multi-bit cell can hold as many as eight bits; when combined with FaStack stacking, this enables capacities as large as 8 Gbit without increasing the footprint.