# US 2021/0240445 A1 · True random number generation and physically unclonable functions using voltage control of magnetic anisotropy effects in stt-mram > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0240445 A1 - Document ID: US20210240445A1 - Status: Published application - Kind: A1 - Application number: 16/776,909 - Filed: 2020-01-30 - Published: 2021-08-05 - Earliest claimed: 2020-01-30 - Assignees: GlobalFoundries U.S. Inc. - Applicants: GLOBALFOUNDRIES U.S. Inc. - Inventors: Hemant M. Dixit; Julien Frougier; Bipul C. Paul; William J. Taylor, JR. - Web page: https://patentgrep.com/patent/US20210240445A1 ## CPC - G06F 7/588: {Random number generators, i.e. based on natural stochastic processes} - G11C 11/1673: {Reading or sensing circuits or methods} - G09C 1/00: Apparatus or methods whereby a given sequence of signs, e.g. an intelligible text, is transformed into an unintelligible sequence of signs by transposing the signs or groups of signs or by replacing them by others according to a predetermined system (cryptographic typewriters G09C3/00) - G11C 7/24: Memory cell safety or protection circuits, e.g. arrangements for preventing inadvertent reading or writing; Status cells; Test cells - G11C 11/161: {details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell} - G11C 11/1675: {Writing or programming circuits or methods} - G11C 11/1693: {Timing circuits or methods} - G11C 11/1695: {Protection circuits or methods} - G11C 11/1697: {Power supply circuits} - G11C 2029/4402: {Internal storage of test result, quality data, chip identification, repair information} - G11C 2029/5002: {Characteristic} - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G11C: STATIC STORES (semiconductor memory devices H10B) - G09C: CIPHERING OR DECIPHERING APPARATUS FOR CRYPTOGRAPHIC OR OTHER PURPOSES INVOLVING THE NEED FOR SECRECY ## Abstract Embodiments of the disclosure provide a system for providing a true random number (TRN) or physically unclonable function (PUF), including: an array of voltage controlled magnetic anisotropy (VCMA) cells; a voltage pulse tuning circuit for generating and applying a stochastically tuned voltage pulse to the VCMA cells in the array of VCMA cells, wherein the stochastically tuned voltage pulse has a magnitude and duration that provides a 50%-50% switching distribution of the VCMA cells in the array of VCMA cells; and a bit output system for reading a state of each of the VCMA cells in the array of VCMA cells to provide a TRN or PUF. ## Claims ### Claim 1 A system, comprising: an array of voltage controlled magnetic anisotropy (VCMA) cells; a voltage pulse tuning circuit for generating and applying a stochastically tuned voltage pulse to the VCMA cells in the array of VCMA cells, wherein the stochastically tuned voltage pulse has a magnitude and duration that provides a 50%-50% switching distribution of the VCMA cells in the array of VCMA cells; and a bit output system for reading a state of each of the VCMA cells in the array of VCMA cells to provide a true random number (TRN) or physically unclonable function (PUF). ### Claim 2 (depends on 1) The system according to claim 1, wherein each VCMA cell in the array of VCMA cells comprises a magnetic tunnel junction (MTJ) device. ### Claim 3 (depends on 1) The system according to claim 1, wherein the array of VCMA cells comprise a spin transfer torque magnetic random access memory (STT-MRAM). ### Claim 4 (depends on 1) The system according to claim 1, wherein the voltage pulse tuning circuit comprises a voltage pulse generator for generating the stochastically tuned voltage pulse. ### Claim 5 (depends on 4) The system according to claim 4, wherein the voltage pulse generator comprises an astable oscillator circuit, a pulse wave modulation (PWM) circuit, or a pseudo-random binary sequence circuit. ### Claim 6 (depends on 4) The system according to claim 4, further comprising a built-in test (BIST) system coupled to the voltage pulse generator, wherein the bit output system provides the TRN or PUF to the BIST. ### Claim 7 (depends on 1) The system according to claim 1, wherein the 50%-50% switching distribution of the VCMA cells in the array of VCMA cells is independent of process, voltage, and temperature variations. ### Claim 8 (depends on 8) The system according to claim 8, wherein the magnitude and duration of the stochastically tuned voltage pulse falls within a range of magnitudes and durations that are dependent upon material properties of the VCMA cells. ### Claim 9 A method for generating a true random number (TRN) or physically unclonable function (PUF), comprising: generating a stochastically tuned voltage pulse; applying the stochastically tuned voltage pulse to a plurality of voltage controlled magnetic anisotropy (VCMA) cells in an array of VCMA cells, wherein the stochastically tuned voltage pulse has a magnitude and duration that provides a 50%-50% switching distribution of the VCMA cells in the array of VCMA cells; and reading a state of each of the VCMA cells in the array of VCMA cells to provide the true random number (TRN) or physically unclonable function (PUF). ### Claim 10 (depends on 9) The method according to claim 9, wherein each VCMA cell in the array of VCMA cells comprises a magnetic tunnel junction (MTJ) device. ### Claim 11 (depends on 9) The method according to claim 9, wherein the array of VCMA cells comprise a spin transfer torque magnetic random access memory (STT-MRAM). ### Claim 12 (depends on 9) The method according to claim 9, wherein the stochastically tuned voltage pulse is provided by a voltage pulse generator. ### Claim 13 (depends on 12) The method according to claim 12, wherein the voltage pulse generator comprises an astable oscillator circuit, a pulse wave modulation (PWM) circuit, or a pseudo-random binary sequence circuit. ### Claim 14 (depends on 9) The method according to claim 9, wherein the 50%-50% switching distribution of the VCMA cells in the array of VCMA cells is independent of process, voltage, and temperature variations. ### Claim 15 (depends on 14) The method according to claim 14, wherein the magnitude and duration of the stochastically tuned voltage pulse falls within a range of magnitudes and durations that are dependent upon material properties of the VCMA cells. ### Claim 16 A system for generating a true random number (TRN) or physically unclonable function (PUF), comprising: a spin transfer torque magnetic random access memory (STT-MRAM), the STT-MRAM including an array of voltage controlled magnetic anisotropy (VCMA) cells; a voltage pulse tuning circuit for generating and applying a stochastically tuned voltage pulse to the VCMA cells in the array of VCMA cells, wherein the stochastically tuned voltage pulse has a magnitude and duration that provides a 50%-50% switching distribution of the VCMA cells in the array of VCMA cells; and a bit output system for reading a state of each of the VCMA cells in the array of VCMA cells to provide the true random number (TRN) or physically unclonable function (PUF). ### Claim 17 (depends on 16) The system according to claim 16, wherein each VCMA cell in the array of VCMA cells comprises a magnetic tunnel junction (MTJ) device. ### Claim 18 (depends on 16) The system according to claim 16, wherein the voltage pulse tuning circuit comprises a voltage pulse generator for generating the stochastically tuned voltage pulse, and wherein the voltage pulse generator comprises an astable oscillator circuit, a pulse wave modulation (PWM) circuit, or a pseudo-random binary sequence circuit. ### Claim 19 (depends on 18) The system according to claim 18, further comprising a built-in test (BIST) system coupled to the voltage pulse generator, wherein the bit output system provides the TRN or PUF to the BIST. ### Claim 20 (depends on 16) The system according to claim 16, wherein the 50%-50% switching distribution of the VCMA cells in the array of VCMA cells is independent of process, voltage, and temperature variations, and wherein the magnitude and duration of the stochastically tuned voltage pulse falls within a range of magnitudes and durations that are dependent upon material properties of the VCMA cells.