Calibrated Temperature Measurement System Using On-Chip Reference Resistors
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Solution Overview
Problem
Existing temperature measurement systems in semiconductor applications face challenges in accurately measuring temperature across varying temperature ranges due to the need for precise resistance measurements of thermistors and reference resistors, which are affected by semiconductor processing defects and mismatch, leading to errors and increased semiconductor area requirements.
Innovation Solution
A calibrated temperature measurement system that includes a resistor, a thermistor, a resistance-to-current converter, and an analog-to-digital converter (ADC) to generate and convert current signals into digital signals, with a calculation stage using resistor-characterization information to determine temperature output values based on resistance ratios, and an on-chip reference resistor for calibration to minimize errors and reduce external component costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If precise resistance measurements of thermistors and reference resistors are performed to achieve accurate temperature measurement across varying temperature ranges, then measurement precision is improved, but device complexity and semiconductor area requirements increase due to the need for compensating processing defects and mismatch
Solution Approach 1:
The patent converts the harmful effect of semiconductor processing defects and mismatch into a beneficial calibration mechanism. By intentionally introducing known test resistors with predetermined resistance values into the measurement system, the defects and mismatch that would normally cause measurement errors are instead used to characterize and quantify the system's behavior. This characterization data is then stored in lookup tables to compensate for the same defects during actual temperature measurements, thereby converting the originally harmful processing variations into a corrective mechanism that improves measurement accuracy without requiring additional complex compensation circuitry
Solution Approach 2:
The patent performs preliminary characterization of the measurement system during the manufacturing process. Test resistors are measured at known temperatures to determine their actual resistance values, and this characterization information is stored in lookup tables before the device is shipped. By performing this calibration action in advance during manufacturing rather than requiring complex real-time compensation during operation, the system achieves high measurement accuracy across varying temperature ranges while keeping the operational device complexity low
2Measurement precision
If precise resistance measurements are performed to achieve accurate temperature measurement, then measurement precision is improved, but manufacturing costs increase due to increased semiconductor area requirements
Solution Approach 1:
The patent converts the harmful effect of semiconductor processing defects and mismatch into a beneficial calibration mechanism. By intentionally introducing known test resistors with predetermined resistance values into the measurement system, the defects and mismatch that would normally cause measurement errors are instead used to characterize and quantify the system's behavior. This characterization data is then stored in lookup tables to compensate for the same defects during actual temperature measurements, thereby converting the originally harmful processing variations into a corrective mechanism that improves measurement accuracy without requiring additional complex compensation circuitry
Solution Approach 2:
The measurement system performs self-characterization during the manufacturing process using the same hardware components that will be used for actual temperature measurements. The test resistors are measured in-situ within the device, and the characterization information is automatically stored in on-chip memory. This self-service approach eliminates the need for external calibration equipment and complex external component assemblies, thereby reducing manufacturing costs while achieving high measurement precision
3Measurement precision
If external reference components are used to achieve accurate temperature measurement, then measurement precision is improved, but device complexity and costs increase
Solution Approach 1:
The patent merges the functions of separate external reference components into integrated on-chip structures. Reference resistors and test resistors are fabricated directly on the semiconductor substrate using the same fabrication processes as the main circuitry. The characterization data from these on-chip reference elements is stored in on-chip non-volatile memory, eliminating the need for external reference components, external calibration equipment, and complex interconnections. This integration reduces both device complexity and component quantity while maintaining measurement precision
Solution Approach 2:
The on-chip reference resistors serve multiple functions: they act as both measurement references for temperature sensing and as calibration test elements for characterizing processing defects. The same hardware infrastructure (ADC, buffer, memory) is used for both the temperature measurement function and the self-characterization function. This multi-functionality eliminates the need for separate dedicated external reference components and reduces the overall system complexity
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
The system achieves high accuracy in temperature measurement across a wide range while reducing semiconductor area and costs by canceling out gain errors and semiconductor processing defects, allowing for relaxed design requirements in the ADC and buffer components.
Implementation Method 1
Devices known as thermistors are known to have a resistances that vary over temperature. Accordingly, some applications measure the resistance of a thermistor in order to track the approximate temperature at which a circuit is operating.
Implementation Method 2
an analog-to-digital converter (ADC) configured to receive a first current signal based on the resistor, convert the first current signal into a first digital signal
Data Source
AI summary
In accordance with some embodiments of the present disclosure, a calibrated temperature measurement system comprises a resistor, a thermistor, a resistance-to-current converter configured to generate a current signal based on a resistance, and an analog-to-digital converter (ADC) configured to receive a first current signal based on the resistor, convert the first current signal into a first digital signal, receive a second current signal based on the thermistor, and convert the second current signal into a second digital signal. A memory may comprise resistor-characterization information. A calculation stage communicatively coupled to an ADC output may be configured to determine a first digital value based on the first digital signal, determine a second digital value based on the second digital signal, calculate a resistance ratio based on the first digital value and the second digital value, and determine a temperature output value based on the resistance ratio and the resistor-characterization information.