A Low Power Real-time On-Chip Power Sensor in 45-nm SOI

Abstract

This paper introduces a real-time on-chip power and temperature sensor for active power management in scaled CMOS technologies. In a distinct departure from earlier power estimation techniques, this sensor measures the voltage drop due to a current load and converts it into pulse counts to get a power estimate in real time. Linear regression is used to estimate load current based on the measured output frequency at a given temperature. The same sensor is also used to estimate temperature in a mode where output time period decreases linearly with temperature. Measurement results show accuracy to within for temperature estimation in the range of 22 -100 and within 10% of the actual power consumed (for loads 3.3 mA). Fabricated in 45-nm SOI technology, this power and temperature sensor occupies an area of and has a power overhead of 120 at 1.2 V supply.Index Terms-Low power, on-chip sensor, power management, power sensor, temperature sensor.

A Low-Area Reference-Free Power Supply Sensor

“…The cell is used in various previous works in the literature, for example [9] and was presented originally in [10], where it was proved to be temperature and process invariant. The inverter cell presented in those works has been modi ed to work as a buffer, just by adding an inverter stage.…”

“…How this comparator stage is tolerant to temperature and process variations is explained in detail in [9] and [10]. The main idea is to have the master switch in a state where its input is always below its threshold voltage.…”

Variation-aware and self-healing design methodology for a system-on-chip

“…On-chip sensors for accurate power estimation are essential for such systems implementing smart power management. In [7], a low power, on-chip power sensor is presented to estimate power consump tion of the circuits in real-time.…”

A PVT-independent Schmitt trigger with fully adjustable hysteresis threshold voltages for low-power 1-bit digitization applications

“…1a) is one of the most effective approaches to realize the voltage comparator for converting the input analog signal to digital signal [5]. Despite the fact that the gain and slew rate is not limited by a bias current and that it provides the maximum possible charging and discharging current for a given supply voltage, it suffers unpredictable inherent threshold voltage caused by PVT variations [10], as shown in Fig. 1b.…”

“…In order to make the threshold voltage of an inverter-comparator controllable and constant under any PVT condition, a self-tuning circuit [10] was introduced in the inverter-comparator circuit, as shown in Fig. 2a.…”