Calibrated Capacitor-Bank Temperature Sensing Across Process Variation
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Solution Overview
Problem
Traditional temperature sensors experience measurement errors due to variations in the wafer fabrication process and the temperatures being measured, which affect calculation accuracy, especially at low temperatures.
Innovation Solution
A temperature sensor design that extends the pulse length of measurement signals by switching capacitor combinations, using multiple capacitors and current sources, and employs a calibration mode to adjust capacitor bank capacitance based on comparison outputs to maintain consistent counting values across fabrication processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional temperature sensor design is used, then the design complexity and occupied area are kept simple, but measurement error increases due to wafer fabrication process variations and temperature variations
Solution Approach 1:
The patent changes the capacitance parameter of the capacitor bank dynamically based on the measured temperature range. By switching between different capacitance values (first capacitance for lower temperature range, second capacitance for higher temperature range), the system maintains consistent counting values across different temperatures and fabrication processes, thereby improving measurement accuracy without requiring complex compensation circuits
2Measurement precision
If traditional temperature sensor design is used, then the design complexity and occupied area are kept simple, but the measurement error increases especially at low temperatures
Solution Approach 1:
The patent specifically addresses low temperature measurement accuracy by introducing a calibration mode that measures and stores calibration data (first calibration data and second calibration data) corresponding to different temperature ranges. During normal operation, the system selects appropriate calibration data based on the current temperature range and uses it to compensate measurements, ensuring consistent accuracy across the entire temperature range including low temperatures
3Measurement precision
If capacitor bank capacitance is fixed, then the design is simple, but the measurement consistency across different fabrication processes deteriorates
Solution Approach 1:
The patent makes the capacitor bank capacitance dynamic by introducing switching circuitry that can change the capacitance value based on the measured temperature range. The system transitions from a static fixed capacitance design to a dynamic adjustable capacitance design, where the capacitance is optimized for different temperature ranges to maintain measurement consistency across various fabrication processes
4Adaptability or versatility
If a single capacitance value is used in capacitor bank, then the design area is minimized, but the adaptability to wide temperature range is reduced
Solution Approach 1:
The patent segments the temperature measurement range into at least two distinct ranges: a lower temperature range and a higher temperature range. For each segment, a specific capacitance value is optimized and selected. This segmentation approach allows the system to adapt to a wide overall temperature range while maintaining measurement accuracy within each segment, effectively trading some design complexity for enhanced versatility
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 solution reduces measurement errors without increasing design complexity or chip area, enhancing measurement accuracy across a wide temperature range, particularly at low temperatures.
Implementation Method 1
a first capacitor bank, a second capacitor bank, a first current source, and a second current source, wherein the first capacitor bank is coupled to a first input terminal of the first comparator, the second capacitor bank is coupled to a first input terminal of the second comparator, the first current source is configured to charge the first capacitor bank using a first current, and the second current source is configured to charge the second capacitor bank using a second current
Data Source
AI summary
There is provided a temperature sensor including a first capacitor bank, a second capacitor bank, a first comparator and a second comparator. In a calibration step, the first comparator compares a first charged voltage of the first capacitor bank with a first group of voltage thresholds to determine conducted capacitors in the first capacitor bank, and the second comparator compares a second charged voltage of the second capacitor bank with a second group of voltage thresholds to determine conducted capacitors in the second capacitor bank. By using the calibration step, the first charged voltage and the second charged voltage across the wafer fabrication process are more consistent and predictable.