Revista mexicana de física
Print version ISSN 0035-001X
The oscillation frequency f0 of a VCO current-starved has been used for sensing temperature ranging from 20 to 99°C. Since f0 is directly proportional to the short-circuit current of the basic cell delay (NOT gate), and taking into account that this current, ISHORT, is directly proportional to the carrier mobility, it is possible to explain how f0 changes as temperature, T, changes too. This oscillator that was manufactured in a CMOS standard process, N-well, 0.5 μm, 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 f0 each 53 ms because the measure step is deduced from the linear fitting applied to the f0 vs. T characteristic.
Keywords : Oscillators; circuits theory; electrical measurements; field effect devices.