The key to studying SSD lies in three components-Master control chip, flash chip and firmware algorithm.

1. Controller 

The controller is the brain of the SSD. Its role is to properly allocate the load of data on each flash chip and to undertake the entire data transfer connecting the flash chip and the external SATA interface. The performance of different master control chips is various, including data processing capabilities, algorithms, and reading and writing control of flash chips, which will directly result in tens of times the difference of SSD products on the performance.

The common brands of controller includes SIMO, PHISON Electronics, Marvell and Samsung.

Actually, SSD is a processer based on ARM architecture/RISC , which makes it have the computing power of CPU. It is as important as CPU. The early controller brands are the leaders of SSD now.

The function of the technology layer includes data transfer, connecting flash chips and external SATA interfaces

Responsible for the entire of various instructions within the SSD: trim, GC and WL.

Important significance: the quality of master chip directly determines the actual experience and service life of SSD. Based on these reasons, the technical threshold of the master control chip is higher, so the related brand is less

SIMO and PHISON: SIMO and PHISON are the master control chip production companies in Taiwan with low costs, which are popular with many manufactories producing SSD in China, including PLEXTOR, Colorful, Galaxy, TECLAST, Gloway, MAXSUN and so on.

Marvel controller: Marvell, which belongs to the high-end category, was originally intended for enterprise use and is now used for the PLEXTOR, SanDisk and Crucial SSD. It has strong technical strength and stable quality of master control chip, but SSD price is relatively expensive.

Samsung master control chip: Samsung master control chip with strong technical strength is only applied in their SSD products. For instance, Samsung 860PRO has the fastest reading and writing speed among SSD with SATA interface. In terms of NVMe SSD, Samsung 960PRO has the fastest reading and writing speed.

2. Flash memory

In addition to controller and cache chip, NAND Flash occupy most other positions on the PCB board. Flash memory is a storage medium, which is a non-volatile memory significantly different from the traditional mechanical disk storage medium. That means that the written data can be saved after power failure, and the unit is a fixed size block rather than a single byte.

There are many types of flash particles. Nowadays, in SSD, the most popular one is NAND Flash memory. Because of its low power consumption, low price and good performance, it is the most important storage material in the storage industry. If these raw materials are not good, the research is in vain and the CPU control is useless. The materials are very important. According to the flash density, NAND Flash chip is divided into SLC (single layer memory unit), MLC (double layer memory unit), TLC (three layer memory unit) and QLC.

3. Firmware algorithm (Technical core secrets of various manufacturers)

The firmware is used to drive the controller. The SSD needs a direct dialogue between the FTL layer and the system. Now, the functions of firmware includes Mapping, Trim, WL , GC and ECC. So there are many algorithms of firmware.

The quality of the firmware is very important. Because of different firmwares, products with the same master control chip and flash particles will have completely different lifetimes and reading and writing performance. This is the most profitable secret of major manufacturers.

The development of good firmware requires perfect compatibility between flash memory and master control chip. It needs to be modified and maintained according to the latest advanced technology and the update of flash particles.

The interface to the component is the SSD. The main interface is SATA, M.2 and PCI-E. SATA and PCI-E use different channels, so they have different speeds. The PCI-E channel is like a highway while the SATA channel is a tortuous mountain road.
Different interfaces need different protocols. The basic protocol of SATA is AHCI while the protocol of PCI-E is NVME. The new OC SSD has their specialized protocols. It's easy to understand, but the technical part is pretty hard.

Related Professional Compulsory Courses

Experts or scholars who are really engaged in the researching the technology of flash memory, whether they are electronic or computer majors, should be proficient in computer architecture, operating system, data structure, embedded principles, C++, Linux. Those who want to study hardware should be proficient in Digital Electronics, analog electronics and the Verilog. The direction of upper application should know the database application management. After all, it is the era of big data. Now, people are paying attention to AI storage and deep learning should also be understood. If you are an expert, it is fine to simulate in high-level language when you have an idea.

Related Articles:

Comprehensive understanding of SSD and NAND Flash (1)

We can trust the quality of QLC SSD

The solid-state disk structure of SSD：master control algorithm ...