A Compact On-chip Analog Memory Cell for Storing TOF Image Signal in CMOS Process

This paper designed and realized a 3
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×3
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CMOS analog memory for storing TOF image signal on chip. In order to achieve high-density integration, NMOS transistor with minimum size is employed to be the switch and the storage capacitor is realized with a 1.8V NMOS transistor. The prototype chip has been fabricated in a standard 0.18μm CMOS process. The size of the memory cell is 4μm
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×4μm
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. The measurement results show that the analog signal can be written into the memory in 20ns, and the leakage current causes the stored analog signal reducing with a speed value of 0.33mV/ms. This memory cell can be expanded to a larger array and integrated into sensor chip.