Input sub-ranging converter system for sampling semiconductor temperature sensors
First Claim
1. A method of sampling a response voltage from a temperature sensor that includes a PN junction, the method comprising:
- generating an offset voltage in response to a digital code;
applying a first bias current to the temperature sensor such that the PN junction produces a first PN junction voltage, and the temperature sensor produces a first response voltage;
combining the offset voltage and the first response voltage to produce a first signal;
applying a second bias current to the temperature sensor such that the PN junction produces a second PN junction voltage, and the temperature sensor produces a second response voltage, wherein the second bias current is different than the first bias current;
combining the offset voltage with the second response voltage to produce a second signal; and
converting the first and second signals to digital codes using a converter that has an input voltage range, wherein the range of response voltages for the temperature sensor is greater than the input voltage range of the converter.
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Abstract
A converter system for a temperature sensor includes a programmable current source, a digital-to-analog converter, a summer, and an analog-to-digital converter. The temperature sensor provides a measurement voltage in response to application of a bias current. The programmable current source selectively provides two different currents to the temperature sensor such that the temperature sensor provides two measurement voltages during a given temperature measurement. The digital-to-analog converter (DAC) provides an intermediate voltage that corresponds to an approximation of a voltage between the two voltages. A summer is configured to produce an offset measurement in response to the intermediate voltage and the measurement voltage. The analog-to-digital converter (ADC) receives the offset measurement voltage and produces a conversion code. Offsetting the measurement voltage reduces the dynamic range requirements of the ADC such that substantially a full input range of the ADC is utilized.
46 Citations
22 Claims
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1. A method of sampling a response voltage from a temperature sensor that includes a PN junction, the method comprising:
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generating an offset voltage in response to a digital code;
applying a first bias current to the temperature sensor such that the PN junction produces a first PN junction voltage, and the temperature sensor produces a first response voltage;
combining the offset voltage and the first response voltage to produce a first signal;
applying a second bias current to the temperature sensor such that the PN junction produces a second PN junction voltage, and the temperature sensor produces a second response voltage, wherein the second bias current is different than the first bias current;
combining the offset voltage with the second response voltage to produce a second signal; and
converting the first and second signals to digital codes using a converter that has an input voltage range, wherein the range of response voltages for the temperature sensor is greater than the input voltage range of the converter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for sampling response voltages from a temperature sensor that includes a PN junction, comprising:
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a means for generating an offset voltage in response to a digital code;
a means for applying a first bias current that is arranged to apply a first bias current to the PN junction such that the PN junction produces a first PN junction voltage, and the temperature sensor produces a first response voltage;
a means for combining the offset voltage that is arranged to combine the first response voltage with the offset voltage to produce a first signal;
a means for applying a second bias current that is arranged to apply a second bias current to the PN junction such that the PN junction produces a second PN junction voltage, and the temperature sensor produces a second response voltage, wherein the first bias current is different from the second bias current; and
a means for converting that is arranged to convert the first and second signals to digital codes, wherein the means for converting has an input voltage range that is less than a range of response voltages associated with the temperature sensor. - View Dependent Claims (15, 16, 17)
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18. An apparatus for sampling response voltages from a temperature sensor that includes a PN junction, comprising:
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a programmable current source that is configured to provide one of a first and second currents when selected to the temperature sensor such that the response voltage from the temperature sensor corresponds to a first voltage when the first current is selected and the response voltage corresponds to a second voltage when the second current is selected;
a controller that is configured to select the first and second currents;
an intermediate voltage selector that is configured to provide an offset voltage during a measurement mode;
a summer that is configured to receive the response voltage and the offset voltage, and provide an offset response voltage by subtracting the offset voltage from the response voltage; and
an analog-to-digital converter that is configured to convert the offset response voltage into a digital code during a measurement mode, wherein the analog-to-digital converter has an input voltage range that is less than a range of response voltages associated with the temperature sensor. - View Dependent Claims (19, 20, 21, 22)
a digital-to-analog converter that is arranged to produce the offset voltage in response to a DAC code that is received from the controller during a pre-measurement mode; and
a comparator that is arranged to compare the offset voltage to the response voltage such that the digital-to-analog converter and the comparator cooperate with the controller to operate as an analog-to-digital converter during the pre-measurement mode.
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20. The apparatus of claim 18, further comprising a temperature calculator that is configured to calculate a temperature value from digital codes that are received from the analog-to-digital converter.
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21. The apparatus of claim 18, wherein the controller is arranged to selectively activate the programmable current source such that the programmable current source applies a multiplicity of the first and second currents in a sequence during the measurement mode.
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22. The apparatus of claim 18, wherein the sequence is one of a random sequence, a pseudo-random sequence, a regular sequence followed by a reverse sequence, and an over-sampling sequence.
Specification