Printed electronics (PE) is a fast-growing field with promising applications in wearables, smart sensors, and smart cards, since it provides mechanical flexibility, and low-cost, on-demand, and customizable fabrication. To secure the operation of these applications, true random number generators (TRNGs) are required to generate unpredictable bits for cryptographic functions and padding. However, since the additive fabrication process of the PE circuits results in high intrinsic variations due to the random dispersion of the printed inks on the substrate, constructing a printed TRNG is challenging. In this article, we exploit the additive customizable fabrication feature of inkjet printing to design a TRNG based on electrolyte-gated field-effect transistors (EGFETs). We also propose a printed resistor tuning flow for the TRNG circuit to mitigate the overall process variation of the TRNG so that the generated bits are mostly based on the random noise in the circuit, providing a true random behavior. The simulation results show that the overall process variation of the TRNGs is mitigated by 110 times, and the generated bitstream of the tuned TRNGs passes the National Institute of Standards and Technology – Statistical Test Suite. For the proof of concept, the proposed TRNG circuit was fabricated and tuned. The characterization results of the tuned TRNGs prove that the TRNGs generate random bitstreams at the supply voltage of down to 0.5 V. Hence, the proposed TRNG design is suitable to secure low-power applications in this domain.

中文翻译：

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一种基于喷墨打印技术的紧凑型低压真随机数发生器

印刷电子 (PE) 是一个快速发展的领域，在可穿戴设备、智能传感器和智能卡中具有广阔的应用前景，因为它提供了机械灵活性以及低成本、按需和可定制的制造。为了确保这些应用程序的运行，需要真随机数生成器 (TRNG) 来为加密函数和填充生成不可预测的位。然而，由于印刷油墨在基板上的随机分散，PE 电路的增材制造工艺会导致高内在变化，因此构建印刷 TRNG 具有挑战性。在本文中，我们利用喷墨打印的可添加定制制造特性来设计基于电解质门控场效应晶体管 (EGFET) 的 TRNG。我们还为 TRNG 电路提出了一种印刷电阻器调谐流程，以减轻 TRNG 的整体工艺变化，以便生成的位主要基于电路中的随机噪声，提供真正的随机行为。仿真结果表明，TRNG 的整体过程变化减少了 110 倍，并且调谐后的 TRNG 生成的比特流通过了美国国家标准与技术研究院的统计测试套件。为了验证概念，建议的 TRNG 电路被制造和调整。调谐 TRNG 的表征结果证明 TRNG 在低至 0.5 V 的电源电压下生成随机比特流。因此，所提出的 TRNG 设计适用于该领域的低功耗应用。