Differential Resistive Sensor Circuit for Stable On-Chip Temperature Sensing
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Solution Overview
Problem
As feature sizes on integrated circuits decrease, the increased density of circuitry leads to higher power consumption and localized temperature rises, making it challenging to implement accurate temperature and resistance sensors, particularly in systems-on-chips (SoCs), with existing bipolar-based sensors experiencing unpredictable accuracy and performance degradation.
Innovation Solution
The use of resistive temperature sensors that incorporate resistors with different temperature coefficients, formed from metal interconnect stacks, to provide a differential temperature signal, utilizing a feedback resistor loop for enhanced accuracy and stability, reducing structural complexity and sensitivity to mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bipolar-based temperature sensors are used in high-density circuitry, then temperature monitoring capability is provided, but accuracy becomes unpredictable and performance degrades
Solution Approach 1:
The patent replaces bipolar-based temperature sensors with a resistive sensor implementation using metal interconnect stacks. This substitution eliminates the unpredictable accuracy and performance degradation associated with bipolar sensors in high-density circuitry, providing stable and accurate temperature monitoring through resistance measurements that are less sensitive to mechanical stress and process variations.
Solution Approach 2:
The patent changes the sensing mechanism from bipolar junction characteristics to resistive properties of metal interconnects. By utilizing the temperature-dependent resistance of metal layers in the interconnect stack, the sensor achieves predictable and stable temperature measurement performance, overcoming the reliability issues of bipolar-based approaches in high-density environments.
2Productivity
If feature sizes decrease to increase transistor density, then more transistors per unit area are achieved, but power consumption and thermal output increase
Solution Approach 1:
The patent utilizes the metal interconnect stacks that are already present in the high-density circuit architecture to provide temperature sensing functionality. By repurposing existing structural elements (the metal interconnects necessary for high-density circuitry) as the sensing element, the system achieves temperature monitoring without adding separate power-consuming sensor structures, thus serving multiple functions with the same components.
3Temperature
If bipolar-based temperature sensors are implemented, then temperature monitoring is achieved, but chip area and structural complexity increase
Solution Approach 1:
The patent makes the metal interconnect stack serve dual functions: maintaining electrical connectivity for high-density circuitry and providing temperature sensing capability. This multi-functionality eliminates the need for separate dedicated sensor structures, thereby reducing chip area while maintaining accurate temperature monitoring capability.
Solution Approach 2:
The patent merges the interconnect structure with the temperature sensor structure by using the same metal interconnect stack for both electrical connection and temperature measurement. This consolidation integrates two previously separate functions into a single structural element, reducing overall chip area and simplifying the implementation.
4Measurement precision
If bipolar junction-based sensors are used, then temperature sensing is provided, but sensitivity to packaging stress increases
Solution Approach 1:
The patent replaces bipolar junction-based sensors with a resistive sensing approach using metal interconnects. This substitution reduces sensitivity to packaging stress because metal resistors exhibit greater mechanical stability and lower piezoresistive effects compared to bipolar junction characteristics, thereby improving measurement precision in stressed packaging environments.
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 proposed sensor circuits achieve accurate temperature sensing with reduced chip area, power consumption, and improved resistance to mechanical stress, maintaining performance comparable to bipolar junction-based sensors while using lower supply voltages and less sensitive to packaging stress.
Implementation Method 1
The resistive sensor circuit includes a first resistor stack and a second resistor stack formed on the substrate. The first resistor stack includes a first set of metal traces and a first set of via holes... The second resistor stack includes a second set of metal traces and a second set of via holes... resistors with different temperature coefficients
Implementation Method 2
The sensor circuit may include an amplifier, an analog-to-digital converter (ADC), and a feedback resistor loop
Data Source
AI summary
An apparatus is provided. The apparatus includes a first resistor stack having a first temperature coefficient. The apparatus also includes a second resistor stack coupled to the first resistor stack having a second temperature coefficient different than the first temperature coefficient. The apparatus further includes a measurement circuit associated configured to determine a temperature of the apparatus based on a differential between a first voltage across the first resistor stack and a second voltage across the second resistor stack and determine a set of resistances of a field-effect transistor (FET) that is coupled to the apparatus based on additional differentials between additional voltages across the first resistor stack and the second resistor stack.