Current Mirror Element Matching for Accurate IC Temperature Sensing
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Solution Overview
Problem
Current temperature monitoring systems on integrated circuits face accuracy issues due to device mismatch in current mirrors, leading to errors and noise in temperature measurement, which can result in overheating and component failure.
Innovation Solution
The dynamic ordered element matching (DOEM) scheme reduces unit element error by sorting and folding unit elements into groups, using fewer elements than conventional methods, thereby improving matching performance and reducing noise and voltage ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional current mirror design is used, then device mismatch causes temperature measurement errors, but increasing the number of unit elements to improve matching increases device complexity and noise
Solution Approach 1:
The current mirror is divided into multiple groups, each containing a specific number of unit elements. This segmentation allows for systematic matching where groups with similar characteristics are paired together, improving temperature measurement accuracy while managing device complexity through organized structure
Solution Approach 2:
The patent changes the organizational parameter from individual unit elements to grouped elements, where each group contains a defined number of units. This parameter change enables better matching statistics without linearly increasing the total number of elements, thus improving measurement precision while controlling device complexity
2Measurement precision
If more unit elements are used to reduce mismatch error, then measurement accuracy improves, but noise and voltage ripple increase
Solution Approach 1:
By segmenting unit elements into groups and selectively activating specific groups based on matching characteristics, the patent reduces the number of simultaneously active elements needed to achieve a given accuracy level, thereby reducing noise and voltage ripple while maintaining measurement precision
Solution Approach 2:
The patent applies local quality by assigning different characteristics to different groups of unit elements. Groups are formed with specific numbers of elements (e.g., groups of 2, 4, 8) and selectively activated based on the required precision level, allowing optimal balance between accuracy and noise reduction at different operating conditions
3Measurement precision
If conventional matching schemes are used, then temperature monitoring accuracy is limited, but implementing high accuracy matching increases device complexity
Solution Approach 1:
The matching scheme is segmented into hierarchical groups where unit elements are organized in groups of 2, 4, 8, or more. This segmentation creates a structured approach to matching that improves accuracy through systematic group pairing while keeping the control logic manageable through the hierarchical organization
Solution Approach 2:
The patent changes the matching parameter from individual element selection to group-level selection. By defining groups with specific element counts and selecting entire groups for activation, the system achieves higher accuracy with simpler control logic compared to individual element matching
Data Source
AI summary
A circuit for high accuracy element matching is provided. The circuit includes an analog to digital converter (ADC) configured to generate an output code. A current source is configured to provide a signal to the ADC. The current source includes a first current branch including a first unit element group having a first unit element coupled by way of a first set of switches to a first node and a second node and a second unit element coupled by way of a second set of switches to the first node and the second node. A second current branch includes a second unit element group having a third unit element coupled by way of a third set of switches to the first node and the second node and a fourth unit element coupled by way of a fourth set of switches to the first node and the second node. A control circuit is configured to provide control signals to the sets of switches based on the output code. The control circuit is further configured to sort unit element currents and to dynamically switch unit elements.