High-Density Physical Random Number Generator Using Spin Signals in Multidomain Ferromagnetic Layer

Figure 3

The randomness test for single- and multidomain pMTJ. (a) Schematic of magnetization arrangement of single- and multidomain ferromagnetic layer. The results of the randomness tests for (b) single cell data and (c) after the XOR operation. For each data set, the 2500-bit sequences are evaluated 400 times (2500 × 400 = 10⁶ bits). Only nine failures are acceptable for each test (point to pass line). In the multidomain data of (b), data 1 (2, 3) means XOR of digitalized data A (B, C) and B (C, A) for 10⁶ bits and data 4 means the XOR of A, B, and C.