Research Of Physical Unclonable Functions Circuit

Physical Unclonable Functions (PUF) is an innovative circuit that can generate keys. It makes full use of theintrinsic process variations in interconnect and transistor to achieve the function that possesses the identification ofchip. In other words, PUF circuit obtains keys by comparing the deviation signals which are generated by the circuitwith the same structure. It can be used in many modern security systems to complete data encryption, authentication,and hardware intellectual property protection and so on. First, the significance and background of PUF circuit areanalyzed in this thesis. Then, many new PUF circuits focusing on the development trends and problems that PUFcircuit faced are proposed, including the design of current type PUF circuit, design of PUF circuit based on theoptimal gate voltage, design of PUF circuit based on SRAM cell circuit and design of PUF circuit based on R-2Rladder digital-to-analog convertor. The reliability of these PUF circuits working under different conditions isanalyzed using Cadence. The research will be carried out as follows:1、Design of Current Type PUF Circuit: By analyzing the current mirror, and combining with the operationgprinciple of PUF circuit, we use the multipath current mirror as the circuit that generates deviation signal andgenerate the random current signal. Then we use the sense amplifier as the output circuit of PUF to compare thedeviation signals and generate response. Eventually, we implement the function of PUF circuit.2、Design of PUF Circuit Based on the Optimal Gate Voltage: First, we analyze the factors that effecting thereliability of PUF circuits. Then, by investigating the theory of Zero Temperature Coefficient about MOSFET andthe property of MOSFET working at this point during process variation, the design of PUF circuit based on theoptimal gate voltage, aiming at improving the reliability of PUF circuit, is proposed.3、Design of PUF Circuit Based on the SRAM Cell: By researching the structure of traditional SRAM-PUFcircuit and the stability about it during reading operation, a highly stable SRAM-PUF cell combining with themethod of improving the stability is proposed. In this design, the isolated NMOSs are inserted between cross-coupleinverter and access transistors of the SRAM-PUF cell to elaborate disruption and improve the static noise margin.At last, it can improve the stability of PUF circuit.4、Design of PUF Circuit Based on R-2R Ladder Digital-to-Analog Convertor: By analyzing the digital-to-analog convertor which outputs analog signal, we determine the structure of the DAC used as the circuit thatgenerates deviation signal. Combining with the approach which improve the reliability of PUF circuit, we simulatethe model of the output voltage. Finally, the response of the PUF circuit is generated with the sense amplifier.The designed circuits above are implemented in TSMC65nm or SMIC65nm CMOS technology. They aresimulated by the tool of Spectre. Monte Carlo simulation results show that the presented circuits havecomprehensive characteristics under different conditions.