Embedded PVT sensors are useful during the test/bring-up phase of SoC development and during the deployment of the part in the field. During the test/bring-up phase, PVT sensors support silicon characterization and binning. They are also used to monitor on-chip variation to validate assumptions made during the design phase. In addition, PVT sensors help to validate power reduction methods such as digital voltage and frequency scaling (DVFS) and adaptive voltage scaling (AVS). A critical parameter for SoCs, power must remain in the target window for two primary reasons:
- To meet system-level power specifications, which are typically a major competitive mandate.
- To meet the heat dissipation specifications for which the chip and package were designed. Exceeding these metrics can result in poor performance and device failure.
After the test/bring-up phase, embedded PVT sensors continue to provide important information about chip operation in the field. The data collected by these devices can be analyzed locally on-chip to optimize performance and security of the design. The data can also be communicated to the cloud via various on-chip interfaces where more complex analysis can be done. Data from many devices assembled in the cloud allows analysis on aggregated system performance.
These types of analyses are focused on two primary goals:
- Keep the device performing as originally intended
- Identify and address unpredicted device issues
With regard to the first item, changes in operating conditions in the field (typically voltage and temperature) can impact device performance. Also, as semiconductor devices age, their performance degrades. Embedded sensors can detect these conditions and implement corrective action to re-center device performance.
With regard to the second item, age or environmentally induced chip failures can occur. Embedded sensors can detect these conditions and on-board logic can implement the appropriate corrective action before catastrophic failures occur. Another form of an unpredicted device issue is a security breach. Many such events have a “signature” indicating they are occurring. Embedded sensors can detect these signatures and on-board logic can take appropriate actions. All these events can also be communicated to the cloud, providing detailed information about system operation in the field.
These tasks are all part of the growing Silicon Lifecycle Management discipline.