Thermal Sensor Calibration Across Digital Power Supply Variations
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Solution Overview
Problem
Thermal sensors in integrated circuits (ICs) face accuracy degradation due to variations in digital power supply, which current calibration methods fail to adequately address, especially in real-time thermal readings from digital domains, leading to significant errors.
Innovation Solution
Implement power supply-based compensation by generating calibrated temperature values for various power supply levels and storing them in e-fuse registers, using control logic to determine accurate thermal readings by relating power supply values to sensor values through a calibration equation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If thermal sensors operate on the same digital power supply as digital units, then power consumption is reduced and area is minimized, but thermal reading accuracy is degraded due to power supply variations
Solution Approach 1:
The patent changes the parameter of power supply voltage to multiple discrete levels (e.g., 0.7V, 0.8V, 0.9V) and performs calibration at each level. This allows the system to capture the relationship between power supply variations and thermal sensor readings, enabling accurate temperature measurement regardless of the actual power supply voltage through interpolation or selection of the nearest calibration point.
Solution Approach 2:
The patent performs preliminary calibration actions by pre-characterizing thermal sensor readings at multiple known power supply voltage levels during manufacturing or initialization. These pre-acquired calibration data points are stored and used during operation to compensate for power supply variations, eliminating the need for real-time complex compensation calculations.
2Device complexity
If thermal sensors operate on the same digital power supply as digital units, then device complexity is reduced, but thermal reading accuracy is degraded
Solution Approach 1:
The patent introduces a calibration parameter dimension (power supply voltage level) without changing the fundamental sensor architecture. The same simple thermal sensor is used, but its readings are adjusted based on pre-stored calibration data corresponding to different power supply voltages, maintaining architectural simplicity while achieving high accuracy.
Solution Approach 2:
The patent creates a virtual model or lookup table of thermal sensor behavior at different power supply voltages through calibration. Instead of modifying the physical sensor, the system uses copied calibration data from controlled calibration conditions to compensate for variations during normal operation, achieving accuracy without increasing hardware complexity.
3Ease of manufacture
If calibration is performed at a single power supply value, then calibration process is simplified, but accuracy is degraded when power supply varies from calibration value
Solution Approach 1:
The patent segments the calibration process into multiple discrete power supply voltage points (e.g., 0.7V, 0.8V, 0.9V) rather than attempting single-point calibration. Each segment represents a specific operating condition, and the system selects or interpolates between segments based on the actual power supply voltage during operation, providing comprehensive coverage without requiring continuous calibration.
Solution Approach 2:
The patent performs calibration at more power supply voltage points than the minimum single point, using a practical number of discrete levels that balances calibration complexity with operational accuracy. This partial multi-point calibration approach provides sufficient accuracy for typical power supply variations without requiring exhaustive calibration at every possible voltage level.
Data Source
AI summary
An integrated circuit includes an analog-to-digital converter (ADC), associated with a thermal sensor, to determine a present power supply value of a power supply voltage for the thermal sensor. E-fuse registers store a set of calibrated temperature values, from the thermal sensor, for each power supply value of a plurality of power supply values. Control logic is coupled to the ADC and the e-fuse registers. The control logic reads the present power supply value from the ADC and generates, based on the present power supply value and the plurality of power supply values, a calibration equation that relates calibrated temperature values to thermal sensor values for the present power supply value.