Interdigitated HEMT Current Sensing With Lower Power Loss
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Solution Overview
Problem
Current methods for current sensing in power electronic systems, such as using sensing resistors and multi-finger high electron mobility transistors (HEMTs, face challenges with high power dissipation and large device size ratios, limiting their effectiveness and efficiency.
Innovation Solution
The implementation of an interdigitated device with a two-dimensional electron gas (2-DEG) conductive path and a sense field effect transistor (FET) within a multi-finger HEMT, which includes a discontinuity in the source finger to form a sensing element, allowing for a significant reduction in chip size while maintaining high sensing accuracy through the use of isolation structures and resistors to enhance resistance and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensing resistor is used for current sensing, then current sensing is achieved, but high power dissipation occurs
Solution Approach 1:
The patent replaces the traditional sensing resistor (passive component) with an active transistor-based sensing structure that uses field effect to measure current. The sensing transistor operates in a high-impedance state during sensing, minimizing power dissipation while maintaining measurement accuracy through voltage monitoring at the source terminal.
Solution Approach 2:
The patent changes the operating parameters of the sensing device by using a transistor with variable channel conductivity controlled by gate voltage. This allows dynamic adjustment of the sensing mechanism to achieve accurate current measurement with minimal power loss, unlike the fixed resistance approach.
2Measurement precision
If multi-finger HEMT is used for current sensing, then sensing accuracy is improved, but the main structure to sensing device ratio becomes excessively large
Solution Approach 1:
The patent divides the HEMT into multiple functional fingers where only specific fingers are dedicated to sensing purposes while others handle main power conduction. This segmentation allows the sensing function to be achieved with a smaller proportion of the total device area, reducing the main structure to sensing device ratio from thousands to a manageable level.
Solution Approach 2:
The patent designs the HEMT structure so that the same device serves dual purposes: main power switching and current sensing. By integrating the sensing function within the existing HEMT architecture rather than adding separate sensing devices, the overall device area is optimized and the area ratio is reduced.
3Measurement precision
If device width is increased to improve sensing accuracy, then sensing precision improves, but design rules limit the range of finger lengths
Solution Approach 1:
The patent applies different design characteristics to different regions of the HEMT device. Specific fingers are optimized for sensing with appropriate width and length dimensions, while other fingers are optimized for power handling. This local optimization allows sensing accuracy to be improved without requiring all fingers to exceed design rule limits.
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 reliable current sensing with a reduced device size and improved performance by increasing the ratio of main structure to sense device size, minimizing power loss, and maintaining high sensing accuracy without increasing the overall device size.
Implementation Method 1
an interdigitated device with a two-dimensional electron gas (2-DEG) conductive path
Implementation Method 2
a sense field effect transistor (FET) within a multi-finger HEMT
Data Source
AI summary
The semiconductor device includes a multi-finger high electron mobility transistor (HEMT). The multi-finger HEMT includes a two-dimensional electron gas (2-DEG); a plurality of source fingers, wherein a first source finger of the plurality of source fingers extends continuously across the 2-DEG, and a second source finger of the plurality of source fingers is discontinuous across the 2-DEG; and a plurality of drain fingers, wherein the plurality of drain fingers is interdigitated with the plurality of source fingers. The second source finger is part of a current sensing element.