Novel Application of Ring-Oscillator-based Sensor for 3D IC Temperature and IR Drop Monitoring

This paper proposes a novel method to clearly differentiate the distinct problems of temperature and IR drop inside a chip. This method involves the placement of two same ring-oscillator-based sensors in specific areas. Simulation results show that as temperature increases, the digital counter output of the ring-oscillator-based sensor decreases. Alternatively, a decrease in the power supply decreases the digital output of the ring-oscillator-based sensor. Results also show that when the digital circuit speed was slow, the difference between the digital count outputs of the two sensors became very small; this difference was very large when the speed was high. Thus, the difference between the digital count outputs of the two sensors represents the internal power status of the chip.