On-chip CMOS temperature sensor with current calibrated accuracy of −1.1°C to +1.4°C (3σ) from −20°C to 150°C

This paper proposes a new sensor circuit to monitor on-chip frequency temperature changes in VLSI circuits. The proposed circuit exploits the temperature dependency of current/voltage of metal-oxide-semiconductor field effect transistor. The variation of current/voltage in the temperature sensor circuit with respect to temperature is subjected to a ring oscillator which provides the relative frequency translation. The circuit is implemented in 0.18μm CMOS technology for a temperature range of -20°C to +150 °C, operates with two point calibration, having an uncertainty of -1.1°C to +1.4°C, consumes a low energy of 0.31nJ per sample and a power consumption of 0.093μW at 12MHz frequency. A switch is used at reference clock frequency to perform self-calibration, hence removing the effects of mismatch and process variation.