Design Considerations for 3D Heterogeneous Integration Driven Analog Processing-in-Pixel for Extreme-Edge Intelligence.

Given the progress in computer vision, image sensors are broadening their capabilities, which requires adding data processing close to or within the pixel chips. In this context, in-pixel computing has emerged as a notable paradigm, offering the capability to process data within the pixel unit itself. Interestingly, state-of-art in-pixel paradigms rely on high-density 3D heterogeneous integration to establish a per-pixel connection with vertically aligned analog processing units. This article provides a comprehensive review of the most recent developments in in-pixel computing and its relation to 3D heterogeneous integration. It offers an in-depth examination of innovative circuit design, adaptations in algorithms, and the challenges in 3D integration technology for sensor chips, thereby presenting a holistic perspective on the future trajectory of in-pixel computing driven by advances in 3D integration.