NAND Flash memory is now a widely accepted non-volatile memory in many application areas for data storage such as digital cameras, USB drive, SSD and smartphones. One form of NAND flash memory, Toggle NAND, was introduced to transmit high-speed data asynchronously thus consuming less power and increasing the density of the NAND flash device.
The initial Toggle NAND versions had memory arranged in terms of SLC (Single Level Cell) or MLC (Multi Level Cell) mode that was considered as a 2D scalar stack and their frequency of operation was also less. The ever-growing demand of high memory capacity and high throughput required further research in the areas like the shrinking size of cell, performance to fill-in these gaps.
Some of these new requirements were incorporated, leading to newer versions of Toggle NAND, namely 3.0 and 4.0, with a re-arrangement of the internal memory developing a 3D layer of memory. With such structures, higher capacity of the memory was possible, but performance was the primary challenge as the latency of the write/read of memory quadrupled with the same frequency.
The key to improving the performance and run the device at very high speed in low power mode was to enhance the frequency of operation for faster read/writes to the memory and reduce the voltage levels.
But with every technology advancement comes some other problems, the next being the data sampling at that high frequency that can cause setup/hold time issues. To overcome these concerns, different types of trainings on the signal interface were made mandatory that shall assist in proper sampling of the data. Few other features for improving the integrity of the signals were added.
The current set of commands were applicable to access the SLC and MLC memory modes but with the 3D layering, these commands were lacking access to the entire set of TLC (Triple Level Cell) and QLC (Quad Level Cell) memory modes. Thus, more commands were required to make sure that the 3D layering was fully written/read.
Main features of Toggle NAND 4.0 :
- High Density of Memory
- High Frequency of operation, greater than 800 MHz
- Data Trainings
Cadence Verification IP for Flash Toggle NAND 4.0 is available to support the newer version of Flash Toggle NAND 4.0, allowing to simulate the memory device for efficient IP, SoC, and system-level design verification. Semiconductor companies can start using it to fully verify their controller design and achieve functional verification closure on it within no time.
Gaurav