Area and error reduction techniques for on-chip temperature sensor

Abstract

Power and thermal problems are one of the major issues on integrated circuits(IC). As transistor’s channel length scales down, the degree of integration is getting higher and power density is also going up. The high power density increase the temperature of IC and it will induce many unwanted situations such as high leakage power, IC’s life-time reduction and even incorrect operation. Even though there are many papers to reduce power consumption of IC, these methods do not care hotspot problem. Hotspot is a point where temperature is going up rapidly. Hotspot cannot be removed by many power management techniques and even make the situation worse. To eliminate hotspot, thermal management techniques should be applied in IC design. However, there are some obstacles to perform thermal management successfully in IC design. One of the obstacles is how to get the hotspot information. The only way to get the information about temperature is to equip temperature sensors in IC, and we need lots of temperature sensors to obtain accurate temperature information. So, the area of temperature sensors is getting larger and this is a problem that we should solve for a successful thermal management. Over the past few decades, temperature sensors equipped in IC has been a voltage-domain type which utilizes Band-Gap Reference (BGR) and Analog-to-Digital Converter (ADC). However, operation voltage (VDD) of IC is going down and it is getting harder to design voltage-domain type temperature sensors. That’s why time-domain temperature sensors have been proposed recently and it is highly expected to be a main type of temperature sensors in the future. In this work, we propose a new temperature sensor based on the time-domain type. Temperature sensors operated in time-domain basically use delay sensitivity about temperature. Mobility of electrons in NMOS and holes in PMOS is getting down with temperature and it makes the smaller current which induces phase difference of inverter delay ...