A True Random Number Generator Based on Spin Torque Nano-Oscillator and Phase Locked Loop

True random numbers, derived from unpredictable physical processes, are essential for ensuring the security of information systems through cryptographic applications such as secure encryption key generation and authentication mechanisms. In this study, we introduce a novel True Random Number Generator (TRNG) architecture leveraging a Spin Torque Nano-Oscillator (STNO) integrated with a meticulously designed phase-locked loop (PLL). The oscillation frequency fluctuations of the STNO, induced by thermal noise, serve as the primary source of entropy. To maximize synchronization, an auxiliary PLL loop is employed to align the rising edges of the sampling signal with those of the entropy source signal. Despite the inherent phase noise of the STNO, the PLL maintains a metastable state between locking and losing lock, further enhancing the randomness and unpredictability of the generated bitstream. Finally, we evaluate and discuss the performance of the proposed TRNG circuit.