Introduction
Nowadays, 3D NAND Flash has attracted great attentions due to its superiority in high storage density [1]–[3]. However, there is a wide negative threshold voltage distribution in 3D NAND Flash memory due to charge trap mechanism [4]. In conventional negative sensing architecture, negative pump and triple well devices are needed to sense memory cells which have negative threshold voltage. But negative pump increases the design complexity of the peripheral circuit, and triple well devices increase the difficulty and cost of the fabrication process. D'alessandro, et al. proposed a method to sense threshold voltage of −2 V without triple well devices and negative pump [5]. But the SA they proposed has disadvantages such as slow read speed, large power consumption and noise.