US Patent 10325646 SRAM physically unclonable function (PUF) circuit and method

The disclosure describes approaches for generating a physically unclonable function (PUF) value. Power is applied to a power control circuit, an SRAM, and a PUF control circuit. After initially powering-up the SRAM, the PUF control circuit signals the power control circuit to disable power to the SRAM. The power control circuit disables power to the SRAM, and then re-enables power to the SRAM after having power to the SRAM disabled for a waiting period. The PUF control circuit reads a PUF value from the SRAM by the PUF control circuit after the enabling of power.