Digital thermal sensor based on ring-oscillators in Zynq SoC technology

The impact of the temperature is one of the most critical issues when designing an industrial embedded systems. Plenty of them are centered on a System-on-Chip, composed of a programmable logic similar to a FPGA and a processing system with one or more processors. Ring oscillators are often used to measure physical parameter such as the temperature in a FPGA. Therefore, this paper presents a ring-oscillator-based digital temperature sensor implemented as an AXI-Lite Intellectual Property on a Xilinx Zynq Z-7020 28 nm System-on-Chip. Both the impact of the measurement time and the number of gates are studied with the objective of getting a fast sensor to give the chip a fast thermal protection. The sensor is then calibrated with a thermal chamber. As a conclusion, even though its architecture is somewhat different from past works, the designed sensor was found to be functional for the targeted application.