OmniVision 15MP/1MP hybrid RGB/event vision sensor (ISSCC 2023)

Guo et al. from Omnivision presented a hybrid RGB/event vision sensor in a paper titled "A 3-Wafer-Stacked Hybrid 15MPixel CIS + 1 MPixel EVS with 4.6GEvent/s Readout, In-Pixel TDC and On-Chip ISP and ESP Function" at ISSCC 2023.

Abstract: Event Vision Sensors (EVS) determine, at pixel level, whether a temporal contrast change beyond a predefined threshold is detected [1–6]. Compared to CMOS image sensors (CIS), this new modality inherently provides data-compression functionality and hence, enables high-speed, low-latency data capture while operating at low power. Numerous applications such as object tracking, 3D detection, or slow-motion are being researched based on EVS [1]. Temporal contrast detection is a relative measurement and is encoded by so-called “events” being further characterized through x/y pixel location, event time-stamp (t) and the polarity (p), indicating whether an increase or decrease in illuminance has been detected.

 

Schematic of dual wafer 4x4 macro-pixel and peripheral readout circuitry on third wafer.

EVS readout block diagram and asynchronous scanner with hierarchical skip-logic.

 

 

Event-signal processor (ESP) block diagram and MIPI interface.

 

Sensor output illustrating hybrid CIS and EVS data capture. 10kfps slow-motion images of an exploding water balloon from 1080p, 120fps + event data.

 

 

Characterization results: Contrast response, nominal contrast, latency and noise vs. illuminance.

 

 

Technology trend and chip micrograph.