METHOD FOR IDENTIFYING USED COUNTERFEIT MICROCHIPS BASED ON THE DEGRADATION PROPERTIES OF SRAM Russian patent published in 2021 - IPC G01R31/30 

FIELD: testing.

SUBSTANCE: invention relates to the field of testing electronics, in particular, determining the time of operation of a static random-access memory and identifying counterfeit products. Substance: unstable bits are counted by entering, at the nominal power supply voltage (V_p = V_nom), a value of 1 or 0 into all bits of the SRAM. The power supply voltage is then reduced to a value selected from the range , guaranteed to be below the critical information retention level of the microchip. All bits of the SRAM are then consecutively transferred along the line of words to the reading mode for a period of time, sufficient for discharging the RC constant of the electrical circuit. Then the contents of the SRAM are read and the number of bits with a change in the value thereof (N) is counted. The microchip of the SRAM with a value of 1 or 0 entered in all cells is subjected to stress impact by means of exposure to an elevated temperature and voltage (V_stress) for a period of time Δt. The method is implemented by means of a combination of counting of unstable bits and at least two iterations of stress impact and counting of unstable bits, wherein, after the first count of unstable bits, the initial number of unstable bits N₀=N is initialised, after the second count of unstable bits, the incremented number of unstable bits is counted relative to the first count of the first iteration of stress ΔN₁=N-N₀, after the third count of unstable bits, the total incremented number of unstable bits is counted relative to the second count after ΔN₂=N-N₀, then the trueness of the expression is calculated, the trueness whereof indicates that the SRAM microchip is "new", and a false value indicates that it is "used".

EFFECT: identification of used SRAM (static random access memory apparatuses) microchips by simple digital equipment without applying precise analogue measuring tools, by means of the standard interface of the microchip, without special requirements for the electrical and topological layout thereof, without a priori primary information about the properties of the physically unclonable functions thereof.

5 cl, 3 dwg