Load-Sense Transistor Arrangement for Current Ratio Accuracy
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Solution Overview
Problem
Existing transistor arrangements face challenges in precisely measuring load current due to parasitic effects that cause deviations in the proportionality factor between the sense current and load current, especially when the size of the sense transistor is reduced, leading to increased losses.
Innovation Solution
The transistor arrangement includes a load transistor and a sense transistor with distinct source conductors having different area-specific resistances, where the sense transistor's source conductor has a higher resistance than the load transistor's, to maintain a precise current proportionality factor independent of the operating point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the size of the sense transistor is reduced to minimize measurement losses, then energy loss is reduced, but measurement precision deteriorates due to increased deviation in the current ratio from the size ratio caused by parasitic effects
Solution Approach 1:
The patent applies local quality by differentiating the source conductor design between the sense transistor and load transistor. The sense transistor is equipped with a first source conductor having a first area-specific resistance, while the load transistor has a second source conductor with a second area-specific resistance. This localized differentiation compensates for parasitic effects in the sense transistor region, maintaining current ratio accuracy even when the sense transistor size is reduced to minimize measurement losses.
Solution Approach 2:
The patent changes the electrical resistance parameter of the source conductors to compensate for parasitic effects. By setting the area-specific resistance of the sense transistor's source conductor differently from that of the load transistor's source conductor, the patent adjusts the electrical characteristics to maintain an accurate current ratio. This parameter change allows the sense transistor to be sized optimally for minimal losses while preserving measurement precision.
2Loss of energy
If the sense transistor is made smaller to reduce measurement losses, then energy efficiency improves, but device complexity increases due to the need for differentiated source conductor designs with specific resistance ratios
Solution Approach 1:
The patent implements local quality by applying different area-specific resistance characteristics to specific regions (sense transistor source conductor vs. load transistor source conductor). This localized approach allows the sense transistor to be minimized for energy efficiency while the differentiated source conductor design compensates for parasitic effects, avoiding the need for more complex global redesigns of the entire transistor structure.
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 design ensures a high proportionality factor between the load and sense currents, minimizing measurement losses and maintaining accuracy across varying operating conditions.
Implementation Method 1
a first source conductor having a first area specific resistance, and a second source conductor having a second area specific resistance, wherein the area specific resistance of the second source conductor is greater than the area specific resistance of the first source conductor
Data Source
AI summary
A transistor arrangement includes a drift and drain region arranged in a semiconductor body and each connected to a drain node, a plurality of load transistor cells each comprising a source region integrated in a first region of the semiconductor body, a plurality of sense transistor cells each comprising a source region integrated in a second region of the semiconductor body, a first source node electrically connected to the source region of each of the plurality of the load transistor cells via a first source conductor, and a second source node electrically connected to the source region of each of the plurality of the sense transistor cells via a second source conductor, a resistance of the second source conductor is different from a resistance of the first source conductor, and the second source conductor comprises an elongated span with a plurality of meanders in which the connection line reverses its direction.