A 8800 μm² CCO-Based Voltage-Droop and Temperature Detector in 65 nm

Abstract

The Vcc level and temperature of IC's are important parameters which determine the power / performance. Resonances in the package and platform can cause significant AC voltage droops which can degrade functionality, requiring additional guard-band. Prior-art droop detectors utilize digital delay circuits, such as tunable replica circuits to measure these droops. However, the delay is a strong function of temperature as well as the DC Vcc level, making it difficult to differentiate the AC droop across different voltage and temperature levels. It is proposed to utilize a current controlled oscillator (CCO) with an analog bias to mitigate the voltage and temperature dependencies, such that only the AC droop is measured. The CCO frequency is independent of the DC Vcc level, while the temperature is also characterized along with the AC droop, such that both temperature and droop levels can be extracted. The sensor can measure droops and temperature to an accuracy of 10mV and ±3 o C respectively. The circuit occupies 8800 μm 2 in 65nm with a power consumption of 297 µW. This circuit is very useful to characterize the power grid in design for test (DFT) applications as well as on-the-fly real time chip operation.