Dynamic Resistor Matching in Sensors for Compact Accuracy
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Solution Overview
Problem
Resistor mismatch in sensor arrays leads to reduced accuracy and increased size requirements, particularly in temperature sensors, where the limited on-chip area necessitates a trade-off between sensitivity and size.
Innovation Solution
A switching resistor array is implemented, where resistors provide different resistance values in alternating cycles, with a dynamic element matching block and operational amplifier controlling current to minimize mismatch, and an analog-to-digital converter averaging digital signals to reduce uncertainty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistor arrays are used in sensor circuits, then measurement precision is improved, but device area increases due to mismatch compensation requirements
Solution Approach 1:
The resistor array is segmented into multiple individual resistors (first resistor, second resistor, third resistor, fourth resistor) that can be independently controlled. This segmentation allows selective activation of resistors based on operational requirements, reducing the need for large compensation networks while maintaining measurement precision through dynamic mismatch compensation.
Solution Approach 2:
The resistor array operates dynamically with switches that can connect or disconnect individual resistors based on operational cycles. This dynamic configuration allows the system to adapt the total resistance and compensate for mismatches in real-time, improving sensor accuracy without requiring a fixed large area for all possible compensation configurations.
2Measurement precision
If multiple resistors are used to compensate for mismatch, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The resistor array with multiple switches serves multiple functions: it provides the primary resistive load for the sensor circuit, enables dynamic mismatch compensation, and allows for flexible resistance adjustment. This multi-functionality reduces the need for separate compensation circuits, thereby managing complexity while improving precision.
Solution Approach 2:
The system implements feedback through the switchable resistor configuration where the total resistance is adjusted based on the sensed conditions and mismatch compensation requirements. The dynamic switching of resistors creates a feedback mechanism that automatically compensates for mismatches, improving precision without requiring complex external control circuits.
Data Source
AI summary
A method and apparatus for dynamically matching a plurality of resistors to a sensor are disclosed. In the method and apparatus, a switching block of a plurality of switching blocks receives a plurality of selection signals. The switching block is coupled to a resistor array having a plurality of resistors that are coupled in series and arranged in a closed loop. Each two resistors are coupled to each other by a respective resistor node of a plurality of resistor nodes. The switching block of the plurality of switching blocks has a plurality of input nodes and an output node, where the output node is coupled to the respective resistor node of the plurality of resistor nodes. In the method and apparatus, the switching block couples an input node of the plurality of input nodes to the output node based on the selection signals.