**5.2 Memristor-based 3D neuromorphic computing**

In the field of ANN designs, a novel 3D neural network architecture, which combines memristors and the monolithic 3D-IC technique, has been proposed [55]. In this structure, neurons and memristor-based synaptic array are stacked vertically, as demonstrated in **Figure 15** [48]. As a non-volatile device, RRAM is capable save static power consumption with small implementation area while maintaining its weighted value. With the monolithic 3D-IC technique, the memristor-based 3D neuromorphic computing can potentially reduce the length of critical path by 3X [56], increase the scalability [52], decrease the power consumption by 50% as well as minify the die area by 35% [57].
