Study on consistency driving method of stitching pixel array based on self-adaptive correction technique

Abstract

With the application of stitching technology in CMOS image sensors of large arrays, the traditional clock tree synchronization design method is not suitable for the two-side drive circuit of pixel arrays, resulting in the serious problems of DC penetration and bad row of the two-side drive of pixel arrays in the same row. In this paper, in terms of the idea of self-adaptive correction on chip, a consistency driving method which can be applied to stitching pixel arrays is proposed. The method can be adapted to the change of chip working environment, and has the characteristics of simple structure and high reliability. Based on 55 nm technology, the present method is applied and verified in a large array CMOS image sensor with 150M pixel size and 77 mm×84 mm chip area of 12 288×12 288. The experimental results show that, under a master clock of 500 MHz and a row clock of 125 kHz, the inconsistency of bilateral row drive is reduced from 17.5 ns to less than 2 ns (one clock period), and the consistency is improved by above than 9 times, ensuring that the frame frequency of the super-array image sensor with a scale of 100 million pixels can reach more than 10 frames.