A Wide Range CMOS Temperature Sensor With Process Variation Compensation for On-Chip Monitoring

Abstract

A fully integrated temperature sensor along with a process compensator based on a frequency to voltage converter is presented in this paper. The proposed temperature sensor uses the difference between a reference current source and a proportional to absolute temperature current source to bias a differential ring-based current-controlled oscillator (CCO). The subtracted current in the CCO generates a linearized temperature-dependent frequency. To adjust the current sources and increase accuracy of the temperature sensor, a process compensator is added in the temperature sensor by adding switches to the architecture. With one point calibration, the maximum inaccuracy of ten measured samples is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-1.9~^{\circ }\text{C}\sim 1.5~^{\circ }\text{C}$ </tex-math></inline-formula> over a temperature range of −40 °C–100 °C. The total power consumption is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$264~\mu \text{W}$ </tex-math></inline-formula> from a 1.5 V supply voltage at 25 °C. The temperature sensor is implemented in a standard 0.18- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS process with an area of 0.0312 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .