Ngo Nguyen Hoai, Shimonomura Kazuhiro, Ando Taeko, Shimura Takayoshi, Watanabe Heiji, Takehara Kohsei, Nguyen Anh Quang, Charbon Edoardo, Etoh Takeharu Goji
College of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577, Japan.
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
Sensors (Basel). 2021 Apr 3;21(7):2506. doi: 10.3390/s21072506.
A burst image sensor named Hanabi, meaning fireworks in Japanese, includes a branching CCD and multiple CMOS readout circuits. The sensor is backside-illuminated with a light/charge guide pipe to minimize the temporal resolution by suppressing the horizontal motion of signal carriers. On the front side, the pixel has a guide gate at the center, branching to six first-branching gates, each bifurcating to second-branching gates, and finally connected to 12 (=6×2) floating diffusions. The signals are either read out after an image capture operation to replay 12 to 48 consecutive images, or continuously transferred to a memory chip stacked on the front side of the sensor chip and converted to digital signals. A CCD burst image sensor enables a noiseless signal transfer from a photodiode to the in-situ storage even at very high frame rates. However, the pixel count conflicts with the frame count due to the large pixel size for the relatively large in-pixel CCD memory elements. A CMOS burst image sensor can use small trench-type capacitors for memory elements, instead of CCD channels. However, the transfer noise from a floating diffusion to the memory element increases in proportion to the square root of the frame rate. The Hanabi chip overcomes the compromise between these pros and cons.
一种名为“Hanabi”（在日语中意为烟花）的突发图像传感器，包括一个分支电荷耦合器件（CCD）和多个互补金属氧化物半导体（CMOS）读出电路。该传感器通过光/电荷导管进行背照式照明，以通过抑制信号载流子的水平运动来最小化时间分辨率。在正面，像素在中心处有一个引导栅极，分支为六个第一分支栅极，每个第一分支栅极再分叉为第二分支栅极，最终连接到12个（=6×2）浮动扩散节点。信号要么在图像捕获操作后读出以重放12到48个连续图像，要么连续传输到堆叠在传感器芯片正面的存储芯片并转换为数字信号。CCD突发图像传感器即使在非常高的帧率下也能实现从光电二极管到原位存储的无噪声信号传输。然而，由于相对较大的像素内CCD存储元件的像素尺寸较大，像素数量与帧数存在冲突。CMOS突发图像传感器可以使用小型沟槽型电容器作为存储元件，而不是CCD通道。然而，从浮动扩散节点到存储元件的传输噪声与帧率的平方根成正比增加。Hanabi芯片克服了这些优缺点之间的折衷。
