Temperature Sensing Method Generating a Temperature Dependent and a Temperature Independent Output Frequencies
Embodiments of the invention concern a temperature sensor comprising: a same oscillator ( 2 ) adapted to alternatively generate a temperature dependent output frequency in a sensing mode and a temperature independent output frequency in a calibration mode, a controller ( 1 ) of said oscillator ( 2 ), adapted to feed said oscillator ( 2 ) with at least a first input signal (VREF), and adapted to change said first input signal (VREF) so as to make said oscillator ( 2 ) switch between generating a temperature dependent output frequency and generating a temperature independent output frequency.
1 . Temperature sensing method comprising:
generating a temperature dependent output frequency in a sensing mode,
generating a temperature independent output frequency in a calibration mode,
using at least an oscillator to generate said output frequencies, wherein both said output frequencies are alternatively generated by the same oscillator,
and wherein switching between generating a temperature dependent output frequency and generating a temperature independent output frequency is performed by changing at least a first input signal of said oscillator.
2 . Temperature sensing method according to claim 1 , wherein switching between generating a temperature dependent output frequency and generating a temperature independent output frequency is performed by changing the dependency, relatively to temperature, of said first input signal of said oscillator.
3 . Temperature sensing method according to claim 2 , wherein switching from generating a temperature dependent output frequency to generating a temperature independent output frequency is performed by making dependent, relatively to temperature, said first input signal of said oscillator, so as to compensate for the dependency, relatively to temperature, of a second input signal of said oscillator, and wherein switching from generating a temperature independent output frequency to generating a temperature dependent output frequency is performed by making independent again, relatively to temperature, said first input signal of said oscillator.
4 . Temperature sensing method according to claim 3 , wherein said second input signal of said oscillator remains temperature dependent, and preferably proportional to temperature, whether in the sensing mode or in the calibration mode.
5 . Temperature sensing method according to claim 3 , wherein said first input signal and said second input signal are permanently compared, and wherein said switching between generating a temperature dependent output frequency and generating a temperature independent output frequency is triggered by a change in the result of said comparison.
6 . Temperature sensing method according to claim 1 , wherein generating a temperature dependent output frequency in a sensing mode includes periodically generating a voltage ramp, variations of said period being representative of temperature variations to be sensed, variations of said period being preferably proportional to temperature variations to be sensed.
7 . Temperature sensing method according to claim 1 , wherein it further comprises using a controller of said oscillator feeding said oscillator with said first input signal, and wherein changing said first input signal is performed by switching between two circuit parts of said controller.
8 . Temperature sensing method according to claim 7 , wherein said switching between two circuit parts of said controller is performed by by-passing a transistor of said controller.
9 . A computer program product comprising a computer readable medium, having thereon a computer program comprising program instructions, the computer program being loadable into a data-processing unit and adapted to cause execution of the method according to claim 1 when the computer program is run by the data-processing unit.
10 . Temperature sensor comprising:
a same oscillator adapted to alternatively generate a temperature dependent output frequency in a sensing mode and a temperature independent output frequency in a calibration mode,
a controller of said oscillator, adapted to feed said oscillator with at least a first input signal, and adapted to change said first input signal so as to make said oscillator switch between generating a temperature dependent output frequency and generating a temperature independent output frequency.
11 . Temperature sensor according to claim 10 , wherein it is adapted to perform the sensing method.
12 . Temperature sensor according to claim 10 , wherein said oscillator comprises a ramp generator.
13 . Temperature sensor according to claim 10 , wherein said controller comprises a temperature dependent current source disposed so that a signal proportional to said temperature dependent current can be duplicated at an input of said oscillator.
14 . Integrated circuit including both a temperature sensor according to claim 10 and a microprocessor relatively disposed sufficiently close to each other so that said temperature sensor can measure the temperature variations of said microprocessor.
15 . User equipment including at least one integrated circuit according to claim 14 , said user equipment preferably being a mobile phone.