A DRAM based Physical Unclonable Function Capable of Generating >10 Challenge Response Pairs per 1Kbit Array for Secure Chip Authentication

A DRAM based Physical Unclonable Function (PUF) utilizing the location of weak retention cells is demonstrated in 65nm CMOS. A new authentication scheme is proposed for the DRAM PUF where a random pattern is written to a small section of the DRAM and then retention failures are induced. To further increase the number of Challenge Response Pairs (CPRs), the data pattern including retention failures is transferred to a different memory location where additional retention failures are induced. This scheme enables more than 10 unique CRPs from a 1Kbit array. To improve the stability of the PUF response, a zero-overhead repetitive write-back technique along with bitmasking was utilized. Voltage and temperature induced instabilities were mitigated by adjusting the read reference voltage and refresh time before each authentication operation. The proposed DRAM PUF has a bit cell area of 0.68μm.