Digital Domain Thermal Sensor Calibration via Logic Deactivation
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Solution Overview
Problem
Existing thermal calibration techniques for digital domain thermal sensors in integrated circuits (ICs) face accuracy degradation due to global and local variations in silicon production, and the inability to turn off the digital power supply, leading to inaccuracies in temperature readings, especially at higher temperatures.
Innovation Solution
The solution involves achieving a zero temperature gradient on the IC die by deactivating digital logic units and using a slower reference clock, allowing for accurate analog thermal sensing through calibration diodes. Additionally, thermal sensors are spatially grouped to determine average thermal values, enhancing calibration accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermal sensors are used on the same digital power supply as digital units, then real-time thermal reads from digital domain areas are enabled, but accuracy of thermal readings is degraded due to global and local variations in silicon production
Solution Approach 1:
The patent introduces local calibration diodes positioned near specific thermal sensor regions, creating localized reference points that account for global and local silicon variations. Each thermal sensor region is paired with a calibration diode in its immediate vicinity, allowing region-specific calibration that compensates for spatial variations in sensor characteristics without requiring system-wide recalibration.
Solution Approach 2:
The patent employs parameter changes by adjusting the operating conditions of thermal sensors during calibration. The calibration process modifies sensor output parameters by comparing readings from thermal sensors against known temperature references from calibration diodes, thereby correcting for accuracy degradation caused by silicon variations while maintaining real-time operational capability.
2Ease of operation
If calibration is performed with digital logic units active, then thermal sensors can be calibrated during normal operation, but temperature gradient across the die prevents accurate calibration
Solution Approach 1:
The patent segments the calibration process into distinct phases: a first phase where digital logic units are deactivated to establish a zero temperature gradient and enable accurate calibration diode readings, and a second phase where digital logic units are activated for normal operation. This segmentation allows calibration to be performed accurately when needed while maintaining operational flexibility.
Solution Approach 2:
The patent applies preliminary action by deactivating digital logic units before calibration to establish a zero temperature gradient condition. This preliminary step ensures that temperature measurements from calibration diodes are accurate before the system transitions to normal operational mode, preventing temperature gradients from compromising calibration precision.
3Measurement precision
If digital logic units are deactivated to achieve zero temperature gradient, then accurate thermal calibration is enabled, but system functionality is reduced during calibration
Solution Approach 1:
The patent implements periodic action by alternating between calibration mode (digital logic units deactivated) and operational mode (digital logic units activated). The system periodically switches between these states, performing accurate thermal calibration when precision is required while maintaining full functionality during operational phases, thus balancing measurement accuracy with system productivity.
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
This approach enables accurate thermal readings by establishing a zero temperature gradient and improving calibration accuracy through spatial averaging of thermal sensor values, reducing errors in temperature measurements and ensuring reliable thermal management in ICs.
Implementation Method 1
analog thermal sensing through calibration diodes
Implementation Method 2
full digital domain thermal sensors
Data Source
AI summary
An integrated circuit includes a plurality of thermal sensors integrated within digital domain circuitry and powered by a digital supply voltage. An activation register receives activation data from a tester unit. Control logic, in response to the activation register being written with the activation data, enters a thermal calibration mode, deactivates a plurality of digital logic units of the digital domain circuitry, and causes a reference clock received from the tester to drive the plurality of the thermal sensors.