Medición de temperatura usando un VCO integrado en silicio

Abstract

The oscillation frequency $f_{0}$ of a VCO current-starved has been used for sensing temperature ranging from 20 to 99$^{\circ}$C. Since $f_{\text{0}}$ is directly proportional to the short-circuit current of the basic cell delay (NOT gate), and taking into account that this current, $I_{\text{SHORT}}$, is directly proportional to the carrier mobility, it is possible to explain how $f_{\text{0}}$ changes as temperature, $T$, changes too. This oscillator that was manufactured in a CMOS standard process, N-well, 0.5 $\mu $m, 5 V, facilitates the integration of circuitry conditioning, which means the feasibility of integrating the whole sensor system in a chip. Digital circuit measures the frequency $f_{\text{0}}$ each 53 ms because the measure step is deduced from the linear fitting applied to the $f_{\text{0}}$ vs. $T$ characteristic.