Temperature Sensor Series Resistance Compensation
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Solution Overview
Problem
Temperature sensors in integrated circuits face measurement-induced errors due to series resistances, which become significant at smaller circuit sizes and have non-obvious temperature dependencies, leading to inaccurate temperature measurements.
Innovation Solution
The method involves adjusting the gain and offset of an analog-to-digital converter to compensate for the temperature coefficients of series resistance by characterizing and calibrating the current densities in the temperature sensing circuit, ensuring constant currents over temperature to reduce measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If series resistance compensation is not implemented, then the temperature sensor can operate with simple circuitry, but measurement accuracy deteriorates due to temperature-dependent errors from series resistances
Solution Approach 1:
The patent applies preliminary action by pre-characterizing the temperature coefficients of series resistances during manufacturing or initial operation. These characterized values are stored in lookup tables or used to pre-calculate compensation parameters, so that during normal temperature sensing operations, the system can quickly apply corrections without performing complex real-time measurements of resistance values.
Solution Approach 2:
The patent introduces an intermediary compensation mechanism that measures the voltage drop across known series resistances separately and subtracts this from the total measured voltage. This intermediary approach isolates the error source (series resistance voltage drop) from the main measurement (junction voltage), allowing for accurate compensation without redesigning the core sensing circuitry.
2Measurement precision
If simple offset compensation is used, then the circuit remains simple, but accuracy deteriorates at smaller integrated circuit sizes where temperature dependency of resistance errors becomes significant
Solution Approach 1:
The patent applies parameter changes by transitioning from a simple fixed offset compensation model to a temperature-dependent compensation model. The system characterizes and stores multiple compensation parameters corresponding to different temperature ranges or conditions, and dynamically selects or interpolates between these parameters based on the current operating temperature, thereby adapting the compensation to match the temperature-dependent behavior of series resistances.
Solution Approach 2:
The patent performs preliminary characterization of the temperature coefficients for each series resistance in the circuit during manufacturing or initial calibration. These pre-determined parameters are stored for use during normal operation, eliminating the need for complex real-time measurements while providing accurate temperature-dependent compensation across the full operating range.
3Measurement precision
If temperature-dependent compensation is implemented, then measurement accuracy improves, but the complexity of error identification and compensation increases
Solution Approach 1:
The patent applies segmentation by dividing the total measurement error into distinct components: the voltage drop across each series resistance (RB and RE) and the actual junction voltage. By measuring or calculating each component separately and applying targeted compensation to each, the system reduces the complexity of identifying and correcting errors compared to treating the total error as a single unanalyzed quantity.
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 improves the accuracy of temperature measurements by accounting for temperature coefficients of series resistance, resulting in a four-fold improvement in accuracy.
Implementation Method 1
When temperature is measured in an integrated circuit, a semiconductor junction is often used in the process. By manipulating the currents and the current densities through the junction, changes in voltage can be measured across the junction.
Data Source
AI summary
An embodiment of the present invention is directed to a method for reducing the effects of temperature coefficients of series resistance in a temperature sensing circuit having a temperature sensing element. The currents through the temperature sensing element are relatively constant over temperature. The method includes adjusting the gain of an analog to digital converter to compensate for the change in current densities in the temperature sensing element multiplied by a characterized temperature coefficient of the series resistance of a signal path of the temperature sensing circuit. The method also includes adjusting an offset of the analog to digital converter to compensate for the change in current densities in the temperature sensing element multiplied by a characterized resistance of the signal path of the temperature sensing circuit.