Calibration of RO-based temperature sensors for a toolset for measuring thermal behavior of FPGA devices

In this work, we present calibration effort for Ring Oscillator-based temperature sensors in Field Programmable Gate Array (FPGA) devices and a toolset suitable for the analysis of thermal behavior of FPGAs. The toolset allows for the automatic synthesis of a unified temperature measurement and heat generation infrastructure combined with the necessary control structures and communication interfaces. The tools insert temperature sensors and heaters based on Ring Oscillators (RO) through the low level manipulations on Xilinx Design Language (XDL) descriptions of FPGA resource allocations. The purpose of the kit is to support rapid setup of thermal behavior experiments by providing basic heating and sensing elements with verified properties as well as an area-optimised IP core for control of the experiments. Furthermore to evaluate inter- and intra-device variability we compare results of temperature sensor calibration using our toolset and six devices from two FPGA families: Spartan-3E and Spartan-6.