1.8V -0.18-μm CMOS Temperature Sensor with Frequency Output

This paper presents a compact frequency output temperature sensor based on the fact that threshold voltage fluctuates according to the temperature. In modern electronic applications, on-chip temperature monitoring is crucial to optimize performance. This paper gives a project of a sensor that has been fabricated using low cost 0.18 $\mu\mathbf{m}$ CMOS technology with a single 1.8 V supply voltage. In order to sense the temperature, the chip get the threshold voltage of the MOSFETs, instead of the usually used base emitter voltage of the bipolar transistor, with the threshold voltage get circuit (VG). Then, with the intention to deal with the high sensitivity voltage signal, VCO is used to transfer the voltage signal into oscillating signal, whose frequency can be seen linearly proportional to the temperature. After one-point trimming, the sensor exhibits a high linearity over a temperature range of 0 to $+150^{\circ} \mathrm{C}$, achieving sensitivity of $3\text{MHz}/^{\circ} \mathrm{C}$ with the inaccuracy rate of 12%. Also, the power consumption is below 1.2 $\mu \mathrm{W}$, and the area of the chip is approximately 0.06 $\text{mm}^{2}$. These features make this design a highly suitable solution in the case of portable applications.