Embedded analog performance monitors for reliable semiconductor circuits and systems

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For mission and safety-critical systems, such as in space, automotive, healthcare or avionic domains, an early detection of potential troubles is necessary to avoid safety issues and keep manufacturing costs low. A similar concern also applies to cheap Internet-of-Things (IoT) ranging from convenience products to near-critical systems. To ensure dependability, it is paramount that semiconductor integrated circuit (IC) manufacturers screen out those devices that contain manufacturing defects, aging and reliability effects, or process shifts beyond the accepted norms. At the core of these methods is the need for fast and accurate test instruments. For measuring analog and radio-frequency (RF) circuit behavior, and more recently microelectromechanical systems (MEMS) devices, a core measurement technology used in both automatic test equipment (ATE) and embedded test is a coherent sampling test methodology. This methodology is optimum in test time and measurement accuracy. The test system consists of a digital-to-analog and analog-to-digital data converter synchronized to a reference sampling clock. Unfortunately, the maximum frequency that the system can operate is limited by the Nyquist sampling principle to ½-times the sampling clock of the data converters. Even the fastest data converters operate with sampling frequencies no greater than 50 GHz. This sets the upper operating frequencies to less than 25 GHz. With advances in long-haul digital and optical communications reaching data rates as high as 400 Gbps, measurement difficulties are sure to follow. Similarly, with the development of 5th-generation wireless systems, operating frequencies of 28 GHz and 70 GHz, will suffer a similar fate. In either case, the existing coherent sampling test methodology cannot be applied. Recently, the applicant has developed a new test methodology based on coherent subsampling. While subsampling has been used for decades in microwave instrumentation and other applications, this work sets out to develop a legally-traceable embeddable test instrument that can be calibrated to an external DC level; possibly supplied by an existing ATE.