Temperature Sensor Calibration Using Ramp Voltage References
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Solution Overview
Problem
Integrated circuits face reliability and robustness issues due to localized high temperature areas, known as hot spots, which existing temperature sensing methods struggle to accurately address, especially since they require fast clocks not always available.
Innovation Solution
A temperature sensing circuit using twin 1st-order temperature independent single slope ramp voltage references and a digital counter for time-to-digital conversion, with programmable capacitors and bias currents for calibration, allowing accurate temperature sensing with slower clocks and minimizing errors from process-voltage-temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single slope ramp based time-to-digital converter is used for temperature sensing, then temperature measurement precision is improved, but the device complexity increases and requires a very fast clock that is not available on every integrated circuit
Solution Approach 1:
The patent divides the temperature sensing function into separate modular components: a temperature sensing circuit that generates a temperature-dependent voltage, a time-to-digital converter that measures the time for a ramp voltage to reach the temperature-dependent voltage, and a clock circuit. This segmentation allows the TDC to be implemented with simpler logic that can operate with slower clocks available in standard integrated circuits, while still achieving precise temperature measurements through the dedicated sensing circuitry.
Solution Approach 2:
The patent introduces a ramp voltage as an intermediary signal that mediates between the temperature sensing circuit and the digital counter. The ramp voltage linearly increases over time and is compared against the temperature-dependent voltage, allowing the conversion of temperature information into a measurable time interval that can be counted by a digital counter using a slower clock, thus reducing device complexity while maintaining measurement precision.
2Speed
If a very fast clock is used in the time-to-digital converter, then temperature sensing speed is improved, but the adaptability decreases because such fast clocks are not available on every integrated circuit
Solution Approach 1:
The patent designs a time-to-digital converter that can function universally across different integrated circuit types by using a clock circuit that can be implemented with standard clock speeds available in most ICs. The converter's design allows it to achieve accurate temperature measurements regardless of the specific clock frequency, making it adaptable to various integrated circuit applications without requiring specialized fast clock infrastructure.
Solution Approach 2:
The patent enables the temperature sensing system to adapt to different clock speeds by allowing the measurement time and resolution to be adjusted based on the available clock frequency. The time-to-digital converter can accommodate variations in clock parameters, ensuring consistent temperature measurement accuracy whether using faster clocks in high-performance ICs or slower clocks in standard ICs, thus improving versatility across different platform capabilities.
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 provides accurate temperature sensing with slower clocks, effectively addressing hot spots in integrated circuits by calibrating ramp slopes and reducing errors from PVT variations, thus enhancing the reliability and robustness of the circuits.
Implementation Method 1
uses a base-emitter voltage of a bipolar device
Data Source
AI summary
A temperature sensor configured to, after a predetermined number of stop counting assertions, determine the temperature dependent voltage and thus the temperature at the output of a counter. During a calibration phase, when a counter value is not equal to a test counter value in a pulse generator circuit, capacitance of the temperature sensor is adjusted until the counter value is equal to the test counter value.