A Physical Unclonable Function (PUF) using capacitor mismatch in a standard successive approximation register analog-to-digital converter (SAR-ADC) as the entropy source is demonstrated in 65nm CMOS. SAR-ADCs are readily available in many system-on-chips, making the hardware overhead of the proposed PUF almost negligible. The inherent process variation of metal-oxide-metal (MOM) capacitors is harnessed through a charge redistribution operation which is sampled by the voltage comparator. To enhance the stability of the PUF output, soft response generation and dynamic thresholding techniques were adopted. Finally, we verify that performing the enrollment operation at a lower operating voltage can ensure that PUF responses are stable at the nominal supply voltage used during authentication.
|Original language||English (US)|
|Title of host publication||2018 IEEE International Symposium on Circuits and Systems, ISCAS 2018 - Proceedings|
|Publisher||Institute of Electrical and Electronics Engineers Inc.|
|State||Published - Apr 26 2018|
|Event||2018 IEEE International Symposium on Circuits and Systems, ISCAS 2018 - Florence, Italy|
Duration: May 27 2018 → May 30 2018
|Name||Proceedings - IEEE International Symposium on Circuits and Systems|
|Other||2018 IEEE International Symposium on Circuits and Systems, ISCAS 2018|
|Period||5/27/18 → 5/30/18|
Bibliographical noteFunding Information:
This paper has presented a PUF employing capacitance mismatch in the charge-redistribution SAR-ADC PUF. Measurement data collected from test chip fabricated in a 65nm process shows an average intra-chip HD of 0.0046 and an average inter-chip HD of 0.508 with a supply voltage ranging from 0.8V to 1.2V. The margin between the maximum inter-chip HD and the minimum intra-chip HD is 0.208 implying a good uniqueness for secure authentication. Future work will be directed towards investigation of machine learning attacks for SAR-ADC PUFs, evaluation of reliability, randomness and uniqueness of the SAR-ADC PUFs under different voltage, temperature, and environmental noise conditions. Effect of aging for MUX PUFs has been studied in . Future research could also be directed towards studying effect of aging on SAR-ADC PUFs. ACKNOWLEDGEMENTS This research was supported in part by the National Science Foundation under grant number CNS-1441639 and the Semiconductor Research Corporation under contract number 2014-TS-2560.
- Physical Unclonable Function (PUF)
- Successive Approximation (SAR) ADC
- capacitance variation
- charge redistribution