Heterogeneous SoC devices, including sensors, analogue and mixed-signal front-end circuits and the availability of massive digital processing capability, are being increasingly used in safety-critical applications like in the automotive, medical, and the security arena. Already a significant amount of attention has been paid in literature with respect to the dependability of the digital parts in heterogeneous SoCs. This is in contrast to especially the sensors and front-end mixed-signal electronics; these are however particular sensitive to external influences over time and hence determining their dependability. This paper provides an integrated SoC / IP approach to enhance the dependability. It will give an example of a digitally-assisted mixed-signal front-end IP which is being evaluated under its mission profile of an automotive tyre pressure monitoring system. It will be shown how internal monitoring and digitally-controlled adaptation by using embedded processors can help in terms of improving the dependability of this mixed-signal part under harsh conditions for a long time.
Analog and mixed-signal IPs are increasingly required to use digital fabrication technologies and are deeply embedded into system-on-chips (SoC). These developments append more requirements and challenges on analog testing methodologies. Traditional analog testing methods suffer from less accessibility and control with regard to these embedded analog circuits in SoCs. As an alternative, an embedded instrument for analog OpAmp IP tests is proposed in this paper. It can provide the exact gain and offset values of OpAmps instead of only pass/fail result. What's more, it is an non-invasive monitor and can work online without isolating the DUT Opamp from its surrounding feedback networks. Nor does it require accurate test stimulations. In addition, the monitor can remove its own offsets without additional complex self-calibration circuits. All self-calibrations are completed in the digital domain after each measurement in real time. Therefore it is also suitable for agingsensitive applications, in which the monitor may suffer from aging mechanisms and has additional offset drifts as well. The monitor measurement range for offset is from 0.2mV to 70mV, and for gain it is from 0dB to 40dB. The error for offset measurements can be 10% of the measurement value with plus/minus 0.1mV, and -2.5dB for gain measurements.
SoCs used in safety-critical applications need to be dependable. However in the deep-submicron region, different kinds of aging effects like negative bias temperature instability (NBTI) make the SoCs, especially the analog/mixed-signal parts, undependable. In this paper, a dependability-improved Opamp is designed based on gain programmability and digital gain monitoring. To accomplish an extra gain range for tuning in 65nm technology, a new voltage-gain boosting method is proposed to provide a maximum 92dB gain in a single amplification stage. The NBTI influence is investigated using Cadence RelXpert and dependability properties for the Opamp are provided.
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