In this work, we present a novel design of physical unclonable function (PUF) based on the topology of current mirror array (CMA). The proposed strong PUF exploits the randomness in the current mirror transistors and generates the response bit by comparing the accumulated current values. Thresholding and reference current are used to increase the reliability of the proposed PUF without requiring additional hardware resources. The proposed PUF structure is also analysed in terms of its difficulty of model building for measurement-prediction attack. Measurement results on 0.35μm test chips demonstrate that the proposed PUF outperforms other state-of-the-art designs with smaller area/bit of 9 × 10−36μm2 and lower native bit error rate (BER) of 0.16%.