In-field Built-in Self-Test for Detecting Incipient Faults in Analog Reconfigurable Filters

Abstract

In critical applications, a fault in the analog sections of a complex integrated circuitimplies severe risks, compromising the mission or potentially causing harm to thepeople or the ambient. In this context, detecting faults during the operation in the fieldbecomes mandatory, and built-in self-test (BIST) arises as suitable for this purpose.This paper presents an innovative user-oriented in-field BIST solution for switchedcapacitor(SC) filters embedded in analog-configurable PSoC™ analog coprocessor(PSoC-AC) from Infineon Technologies AG. The BIST targets catastrophic faults inswitches and deviation faults in capacitors, adopting the single-fault paradigm. Themethod is based on comparing the time-domain responses of the filter (for step input)against a pre-established pattern using a low computational cost signal similarity measure(SSM). The scheme implements the test signal generator and response analyzerwith the resources available in the selected platform. This, along with the simple SSMused, achieves zero hardware overhead and low penalty in the memory available forthe user application. Themethod does not require sophisticated signal processing techniques,reducing it to a simple offset removal process. The paper reports an extensiveexperimental fault injection and measurements campaign. Additionally, it extends theevaluations through fault simulation characterization using a low-cost filter model toestablish the lowest deviation fault the method can detect in capacitors. The resultsshow an outstanding performance, detecting all the considered catastrophic faults.Regarding deviation faults, the method detects incipient ones, which is a relevantaspect because the BIST can detect degradations at an early stage.