Digitizing temperature measurement system and method of operation
First Claim
1. A method for sampling and digitizing a temperature measurement from a first temperature sensing element, comprising:
- applying a first excitation source to said first temperature sensing element;
generating an input voltage step at said first temperature sensing element as a result of said application of said first excitation source;
AC coupling said input voltage step to an integrator;
integrating charges corresponding to a transition of said input voltage step on an accumulation capacitor;
generating entirely in the charge domain a charge domain reference signal;
applying said charge domain reference signal to said integrator;
generating a data dependent signal for deactivating or activating said integrator;
integrating charges corresponding to a reference charge packet associated with a transition of said charge domain reference signal on said accumulation capacitor when said data dependent signal has a first value or disregarding said charges corresponding to said reference charge packet when said data dependent signal has a second value, said transition of said charge domain reference signal being opposite to said transition of said input voltage step;
comparing a signal corresponding to said charges accumulated on said accumulation capacitor with a reference level; and
generating an output signal as a result of said comparing, said data dependent signal having said first value and said second value corresponding to respective logical levels of said output signal;
wherein after a plurality of sampling cycles, said output signal forms a digital data stream having an ones density proportional to a magnitude of said input voltage step.
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Abstract
A digitizing temperature measurement system for providing a digital temperature measurement includes an excitation source for providing switched excitation currents to two or three temperature sensing elements and an ADC circuit including a charge-balancing modulator and a digital post processing circuit. The system utilizes synchronous AC excitation of the temperature sensing elements and an AC coupled analog-to-digital converter input. The temperature measurement system also implements correlated double sampling for noise cancellation to provide low noise and highly accurate analog-to-digital conversions. The modulator receives a charge domain reference signal generated by a reference charge packet generator incorporating a charge based bandgap subsystem. Therefore, the temperature measurement system can be operated at very low supply voltages, such as 1.0 Vdc. A low noise and highly accurate temperature measurement system is thus realized where temperature measurements of very high resolutions (up to 16 bit) can be attained.
95 Citations
16 Claims
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1. A method for sampling and digitizing a temperature measurement from a first temperature sensing element, comprising:
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applying a first excitation source to said first temperature sensing element; generating an input voltage step at said first temperature sensing element as a result of said application of said first excitation source; AC coupling said input voltage step to an integrator; integrating charges corresponding to a transition of said input voltage step on an accumulation capacitor; generating entirely in the charge domain a charge domain reference signal; applying said charge domain reference signal to said integrator; generating a data dependent signal for deactivating or activating said integrator; integrating charges corresponding to a reference charge packet associated with a transition of said charge domain reference signal on said accumulation capacitor when said data dependent signal has a first value or disregarding said charges corresponding to said reference charge packet when said data dependent signal has a second value, said transition of said charge domain reference signal being opposite to said transition of said input voltage step; comparing a signal corresponding to said charges accumulated on said accumulation capacitor with a reference level; and generating an output signal as a result of said comparing, said data dependent signal having said first value and said second value corresponding to respective logical levels of said output signal; wherein after a plurality of sampling cycles, said output signal forms a digital data stream having an ones density proportional to a magnitude of said input voltage step. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification