Applying IJTAG-compatible embedded instruments for lifetime enhancement of analog front-ends of cyber-physical systems

In safety-critical cyber-physical systems, analog front-ends combined with many-processors are being increasingly employed. An example is an imminent collision detection chip for cars. Such a complex system requires zero downtime and a very high dependability despite aging issues under harsh environmental conditions. By on-line monitoring the health status of the processor cores and taking appropriate counteractions if required, we have accomplished this goal in the past via IJTAG compatible embedded instruments and appropriate embedded software. This paper extends this approach to the analog / mixed-signal frontends of these systems, thereby creating a new uniform approach in design & test methodology, as well as a streamlined fault management. An IJTAG-compatible voltage monitor is introduced, for measuring aging-generated offset in OpAmps and SAR ADCs, as well as a delay-monitoring embedded instrument for detecting timing issues in ADCs. In addition, two-stage counter measures, like digitized recalibration and subsequent replacement, are presented to increase the lifetime by factors of the analog front-end of Cyber-Physical Systems-on-Chips