A Study Of True Random Number Generator Based On The Delay Of NbO_x Threshold Switching Memristor

The true random number generator(TRNG),which is the core component of the encryption system,provides unpredictable and independent random numbers that offering data support for the security of the password generated by the encryption system.The variation in the resistance state,jump delay and other physical quantities in the memristor are truly randomly distributed.Besides,due to the outstanding advantages such as high integration,fast operation speed,and low energy consumption,the memristor has attracted significant interest in many fields.However,the study of the TRNG based on the memristor mainly focuses on the improvement of random number output rate and randomness.The influence of device parameters and circuit parameters for the true random number have not been studied,which hinder the application in the real world.In this paper,a TRNG circuit based on the delay characteristics of threshold switching memristor is studied,including design and fabrication and implementation,characterization analysis and model construction of threshold switch memristor,design and implementation of TRNG circuit,and the influence factor of device parameters and circuit operating parameters on circuit performance,etc.The main work of the thesis is as follows:In,Chapter 2,an NbO_x threshold switch memristor is designed and fabricated according to the device requirements of the TRNG design.And the external characteristic model of the threshold switch memristor is established to provide support for the design of the TRNG.The mechanism of the NbO_x threshold switch memristor is analyzed in the first part of this chapter,which clarifies the key physical factors that affect the performance of the device.It provides support for the design,preparation,and performance improvement of the device.In the second part,a NbO_x threshold switch memristor is designed and fabricated.Then the fabrication process and detailed parameters is introduced.In the third part,the electrical characterization of the NbO_xthreshold switch memristor is performed,and the key performance parameters such as the threshold voltage,hold voltage,switch resistance state,and jump delay of the device are extracted.In the fourth part,a model of the external characteristics of the threshold switch memristor is constructed based on the measured parameters,and the function of the model is verified by simulation.In Chapter 3,a rate-adjustable TRNG circuit based on the delay of the threshold switch memristor is designed.Then the circuit function of the random number generator and the randomness of the output data is verified through simulation and experiments.In the first part of this chapter,a rate-adjustable TRNG based with the randomness of the transition delay of the threshold switch memristor on the 1T1R structure is designed.The random number generation rate can be adjusted by changing the gate voltage.Then the circuit function is verified by simulation.The NIST standard tests verified the randomness of the output data of the designed circuit.In the second part,the board-level implementation of the circuit with the NbO_x threshold switch memristor is achieved.The basic functions and output randomness of the circuit is verified through experiment.The experimental results are consistent with the design goals and simulation results.In Chapter 4,the device parameters of threshold switch memristor and working parameters of circuit on the performance of TRNG circuits is studied by combining the two verification methods of simulation and experiments.In the first part of this chapter,the influence of device parameters on the output rate and randomness of the random number generator is studied.The device parameters are divided into three aspects:device resistance state,threshold voltage and jump delay.The simulation verifies that the corresponding changes of parameters affect the circuit output rate and randomness.In the second part,the influence of the circuit working parameters on the output of the random number generator is studied.The work parameters are also divided into three aspects:input voltage amplitude,the NMOS transistor gate voltage and the output sampling window.The influence and mechanism of circuit output rate and randomness is then verified by experimental tests.In Chapter 5,the main contributions of this thesis are summarized and the prospects for future work is performed.