Design of a CMOS Image Sensor with Bi-Directional Gamma-Corrected Digital-Correlated Double Sampling

Abstract

We present a 640 × 480 CMOS image sensor (CIS) with in-circuit bi-directional gamma correction with a proposed digital-correlated double sampling (CDS) structure. To operate the gamma correction in the CIS, the transfer function of the analog-to-digital converter can be changed by controlling the clock frequency of the counter using analog CDS. However, the analog CDS is vulnerable to capacitor mismatch, clock feedthrough, etc. Therefore, we propose a digital-CDS method with a hold-and-go counter structure to operate the bi-directional gamma correction in the CIS. The proposed CIS achieves a 10-bit resolution using a global log-exponential counter and configurable column reset counter with a resolution of 8/9 bits. The sensor was fabricated in a 0.11 μm CIS process, and the full chip area was 5.9 mm × 5.24 mm. The measurement results showed a maximum SNR improvement of 10.41% with the proposed bi-directional gamma-corrected digital-CDS with the hold-and-go counter. The total power consumption was 6.3 mW at a rate of 16.6 frames per second with analog, pixel, and digital supply voltages of 3.3 V, 3.3 V, and 1.5 V, respectively.

A Self-Rectifying Synaptic Memristor Array with Ultrahigh Weight Potentiation Linearity for a Self-Organizing-Map Neural Network

“…The SR-synaptic array can conduct high-quality image filtering within the device array with good reliability and repeatability. Compared to traditional CMOS circuits, , this array requires a simpler peripheral circuit and has a smaller area and power consumption. As a result, it is a promising technology for the development of high-performance artificial visual systems.…”

Design of Low-Noise CMOS Image Sensor Using a Hybrid-Correlated Multiple Sampling Technique

“…As various technologies, such as the Internet of Things (IoT) and self-driving cars, have developed, CMOS image sensors (CISs) go beyond the role of sensing on behalf of the human eye and require the ability to recognize objects, even in situations where it is difficult to observe them with the human eye [1][2][3]. To this end, various circuit techniques have been proposed to obtain high-quality images by increasing the dynamic range or reducing dark random noise (DRN) [4][5][6]. In general, CIS uses a correlated double sampling (CDS) technique to reduce readout noise by sampling the output voltages of the pixel twice.…”