Temperature Sensor Calibration Using Voltage-Based Constant Derivation
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Solution Overview
Problem
Calibration of temperature sensors in integrated circuits is challenging, especially for delta-Vbe sensors, as forcing a known temperature can be difficult, and existing methods vary widely, making it hard to achieve accurate calibration without precise temperature control.
Innovation Solution
A method and apparatus that generate digital values based on voltages applied to a temperature sensor circuit, using arithmetic circuitry to derive a constant for temperature calibration, which includes determining an initial and final value of the constant using external and internal voltages, and accounting for voltage offsets, allowing calibration without a known temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a known temperature is used for calibration, then temperature sensor accuracy can be improved, but the complexity and difficulty of the calibration process increases due to the need for precise temperature control
Solution Approach 1:
The patent introduces voltage as an intermediary parameter to replace temperature as the calibration reference. Instead of directly controlling and measuring temperature during calibration, the system uses voltage measurements from the bandgap circuit to derive calibration constants. This intermediary approach eliminates the need for temperature control equipment while maintaining calibration accuracy.
Solution Approach 2:
The patent substitutes the mechanical/physical temperature control system with an electrical voltage-based calibration system. By replacing temperature references with voltage references and using electrical measurements to derive calibration constants, the system eliminates the need for thermal chambers, temperature sensors for calibration, and complex temperature control mechanisms.
2Reliability
If traditional calibration methods are used, then temperature sensor calibration can be achieved, but the ease of operation decreases due to the need for precise temperature control equipment
Solution Approach 1:
The calibration process becomes self-service by using the temperature sensor's own internal voltage outputs as the calibration reference. The system automatically measures voltages from the bandgap circuit, processes these voltages through arithmetic operations, and derives calibration constants without requiring external calibration equipment or manual temperature control. The sensor essentially calibrates itself using its inherent electrical characteristics.
3Ease of operation
If voltage-based calibration is used, then the ease of operation improves by eliminating temperature control equipment, but the measurement precision may be affected by voltage measurement accuracy
Solution Approach 1:
The patent implements feedback by continuously measuring voltages from the bandgap circuit during normal operation and using these voltage measurements to update or verify calibration constants. The system processes voltage outputs from the temperature sensor circuitry itself, creating a closed-loop feedback mechanism that ensures measurement precision while maintaining ease of operation. The arithmetic circuit continuously refines calibration based on actual voltage measurements.
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
Enables accurate calibration of temperature sensors by deriving a constant based on voltage values, improving temperature reading accuracy and simplifying the calibration process by using known voltages, reducing the need for precise temperature control.
Implementation Method 1
Temperature sensed by a delta-Vbe sensor may be determined by voltages across, e.g., two different PN junctions (such as base-emitter junctions of corresponding bipolar transistors) and calculating temperature based on a difference between the voltages
Data Source
AI summary
A method and apparatus for calibrating a temperature sensor is disclosed. In one embodiment, a method comprises generating first and second digital values based respectively on first and second voltages applied to a portion of a temperature sensor circuit. An arithmetic circuit may derive the value of the second voltage based on the first and second digital values. The method further comprises determining an initial value of a constant based on values of the first and second voltages, and determining a final value of the constant based on the initial voltage and at least one voltage offset. The constant may then be used in determining temperature readings for the temperature sensor.