Workload variation compensation optimization of ring oscillator temperature measurement method and its application in field-programmable gate array

Abstract

—With the ongoing improvements in semiconductor manufacturing technology, the supply voltage required for field-programmable gate array (FPGA) chips is gradually decreasing. As a result, the oscillation frequencies of ring oscillators are affected more obviously by voltage fluctuations, and the sharp changes in the oscillation frequency that can be caused by small changes in the FPGA core voltage have become a problem that cannot be ignored for digital temperature sensors. In this paper, we use a 28 nm FPGA chip to realize a digital temperature sensor network, and at the same time deploy 32 temperature sensors for comprehensive temperature monitoring of the FPGA chip; the monitoring process mainly characterizes the non-ideal influence of the workload changes on the ring oscillator's response. The temperature measurement method, which is based on the oscillation frequency, is modified to compensate for the influence of core voltage variations due to changes in the working load on the output frequency of the ring oscillator. The test results are compared with those from an infrared thermal imager. These results prove that the proposed compensation method can improve the temperature measurement accuracy and ensure that it reflects the actual chip temperature accurately under various working load conditions. This condition is essential for electronic device health monitoring, thermal management, and fault diagnosis scenarios to prevent problems being caused by overheating and to ensure reliable system operation.