Efficient Analog Error Correction for Printed Unary-Encoded Computing

Printed electronics (PE) is an emerging additive manufacturing technology, enabling flexible and extremely lowcost computing devices for future pervasive computing systems. Given the form factor and limited device count in this technology, Unary Encoding (UE), which encodes values as a sequence of bits (1’s or 0’s) by utilizing the proportion of 1’s in the sequence to represent the corresponding probability, shows great promise for printed technologies targeting resource-constrained applications. However, while UE offers some resilience to noise and variability, explicit error correction is still required to address intrinsic defects and variations in printing technologies to deliver reliable and stable outputs. In this work, we propose an area-efficient analog error correction (AEC) method using UE techniques to deal with sporadic bit errors and environmental noise at runtime. This approach significantly reduces transistor count and area utilization compared to conventional error correction coding (ECC) implementations. For proof of concept, we have shown the applicability of this approach for printed physical unclonable functions (p-PUFs) which have significantly lower reliability than silicon-based counterparts. Moreover, the robustness of the proposed scheme against temperature and voltage fluctuations has also been reported. By applying AEC to the p-PUFs output bitstream, its reliability can be fully restored (statistically 100%) for up to 20% bit error rate.