Time Domain and Area Efficient Smart Temperature Sensor Exploiting Channel Length Modulation Coefficient

Abstract

This work suggests an all-digital temperature sensor with a high sampling rate that is based on a time-to-digital converter (TDC). Two on-chip voltage-controlled oscillators (VCOs) are used in the design of the sensor core, which senses temperatures between $-40^{\circ }$C and 200${}^{\circ }$C. For digital code conversion, the outputs of the VCO are fed into two asynchronous counters. In both low- and high- resolution modes, the error following two-point calibration is observed between $-1.08^{\circ }$C and $+1.06^{\circ }$C. The sensor’s ability to function in both high- and low-resolution modes based on conversion time is an important feature. At a sampling frequency of 0.19$$MHz, the maximum resolution achieved is 0.18${}^{\circ }$C. Additionally, the sensor has control logic built in to turn off the sensing as soon as the conversion is complete. At 90-nm process, 1.1$$V supply voltage and 27${}^{\circ }$C, the proposed sensor occupies $0.044{\mathrm{\text{mm}}}^2$ and consumes $817.5\mu \mathrm{\text{W}}$.