Temperature Sensor Arrangement Using Ratio Metric Measurement
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Solution Overview
Problem
Temperature sensors using current integrating modulators face accuracy issues due to manufacturing process variations and temperature drift, leading to less accurate temperature measurements.
Innovation Solution
Incorporating a second resistor with matching resistance values, connected alternately to the current integrating modulator, allows for ratio metric measurement to cancel out process variations and temperature drift, enabling more accurate digital temperature representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a current integrating modulator with an IPTAT current source is used for temperature measurement, then the temperature measurement can be integrated with other sensor functions sharing the same modulator circuitry, but the manufacturing process variations cause substantial calibration requirements and reduced measurement accuracy
Solution Approach 1:
The patent changes the measurement parameter from absolute current values to ratio metric values. By measuring the ratio between the IPTAT current and a reference current, the measurement becomes independent of manufacturing variations and temperature drift, thereby improving temperature measurement accuracy while maintaining integration capability
Solution Approach 2:
The patent introduces a feedback mechanism where the measured temperature is used to compensate for temperature drift in the reference current. This feedback loop ensures that the ratio metric measurement remains accurate across varying temperature conditions, resolving the accuracy issue caused by temperature-dependent variations
2Adaptability or versatility
If a current integrating modulator with an IPTAT current source is used for temperature measurement, then the temperature measurement can be integrated with other sensor functions sharing the same modulator circuitry, but the operating temperature variations introduce additional variations difficult to compensate
Solution Approach 1:
The patent transforms the measurement approach by using ratio metric measurement instead of absolute measurement. This parameter change makes the measurement immune to operating temperature variations, as both the IPTAT current and reference current experience similar temperature drift that cancels out in the ratio, thereby improving measurement stability
Solution Approach 2:
The patent introduces a reference current as an intermediary element that experiences the same temperature variations as the measurement current. By comparing both currents through the same modulator, the temperature effects act as a common-mode signal that can be rejected, improving reliability under varying operating conditions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly enhances the accuracy of temperature measurements by controlling relative resistance values, reducing the impact of manufacturing variations and temperature changes, while maintaining low semiconductor area and reasonable power consumption.
Implementation Method 1
A temperature-sensitive element generates a current that depends on temperature, wherein an increasing temperature generates an increasing electrical current. Practically, the current may be proportional or substantially proportional to the absolute temperature.
Implementation Method 2
The current integrating modulator performs an analog-to-digital conversion translating an analog current to a digital signal using an integrating modulating process. The current integrating modulator integrates the input current onto an integrating capacitor.
Data Source
AI summary
A temperature sensor arrangement includes a current integrating modulator that provides a count value dependent on the current supplied to its input terminal. A temperature-sensitive element includes a resistor to generate a current dependent on temperature. First and second switches alternately connect the temperature-sensitive element and another resistor to the input terminal of the current integrating modulator. The temperature sensor arrangement can be combined with an ambient light sensor sharing the current integrating modulator.