What is CMOS Image sensor ?

On September 2, 2021, Samsung announced the industry's first 200 million pixel mobile image sensor "Isocell HP1." What is an image sensor? Let's see how it works.

 

1. What is Image sensor?

 The sensor used to image digital cameras and objects is called Image Sensor. Currently widely used image sensors include CCD and CMOS sensors.

 When light reflected from an object touches the photodiode of the image sensor, "light" is converted into an electrical signal and transmitted to various internal devices such as serial shift registers, capacitors, and amplifiers in turn. Finally, analog-to-digital conversion takes place. The voltage signal is then converted into binary (0 and 1) values that can be processed and stored.

 

2. CMOS sensor principle  

 MOS stands for Complementary Metal Oxide Semiconductor, a mainstream semiconductor process with low-power, high-speed advantages widely used to manufacture CPU, memory, and various digital logic chips. Next, I will also post about the MOS manufacturing method, which is the basis of semiconductors. Please think that there is a CMOS in the semiconductor manufacturing process easily today.

 

 The image sensor made of CMOS semiconductor is called CMOS Image Sensor (CIS). Image sensors designed based on CMOS processes are more than 90% similar to general-purpose semiconductor processes, especially memory manufacturing processes. The CMOS image sensor switches signals of each photodiode using a CMOS switch, and each cell consists of a photodiode and a CMOS switch as shown below. (Refer to the image below) (Easy memory is a semiconductor with a lot of transistors to store 0 and 1, and CMOS is a semiconductor with a lot of photodiodes that switch from light energy to charge).

 

 When the line drive circuit selects a row, the CMOS switch of the cell output signal is turned on, the CMOS switch of the remaining rows is not turned on, and the photoelectric signal of the line cell is transmitted to the column selection multiplexer. The column selection multiplexer consists of a series of CMOS switches and connects the sequence of signals in this row to the output to complete sequential reading of the signal column. 

CMOS sensor principle   

3. Advances in image sensors

I also have experience in developing camera modules. At that time, Sony was the unrivaled No. 1. LSI Team? (I can't remember clearly) has a strong memory of catching up with Sony, which is currently No. 1 in the world at Samsung Electronics and is expected to remain in this position for the next 10 years. Companies such as Tsinghua Uni have been chasing DRAM RAND memory technology in China, but it is difficult due to U.S. sanctions.

 

 It is also important to increase pixels by increasing semiconductor manufacturing technology, but I personally think that AP development technology that can secure software development personnel and control sensors is more important. It is also important to secure software technology to process 200 million pixels of data accurately and without errors.

Samsung Electronics' mobile image sensors 'Isocell GN5' (left) and 'Isocell HP1' (right)

☞ 200 million pixel isocell HP1 Please refer to the link below for more information.

https://bit.ly/2YetNwF