Interior-Fed Transistor Fingers to Limit Phase Shift and Coupling
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Solution Overview
Problem
High power, high frequency transistors face challenges in maintaining performance due to increased gate finger widths, which lead to electromigration and adverse effects on high frequency performance, and conventional methods to enhance gate periphery either increase die size or introduce phase differences in signal propagation.
Innovation Solution
The solution involves a transistor device design with gate and drain fingers that include a gate bond pad and drain bond pad extending on the fingers, an isolation material between bond wires, and a gate interconnect coupled to the gate finger at an interior position, reducing coupling between input and output bond wires and mitigating phase differences by dividing the gate finger into segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If gate fingers are made wider to increase gate periphery for higher output power, then output power capability is improved, but high frequency performance deteriorates and electromigration occurs
Solution Approach 1:
The gate finger is divided into multiple segments along its length, with each segment connected to the gate interconnect at different positions. This segmentation reduces the effective electrical length of each gate segment, thereby reducing phase differences and electromigration effects while maintaining the total gate periphery width for high output power capability
Solution Approach 2:
An isolation material is introduced between the gate bond pad and drain bond pad to reduce parasitic coupling and capacitance. This intermediary element improves high frequency performance by minimizing unwanted electromagnetic interactions while allowing the gate fingers to maintain their wider dimensions for power handling
2Power
If gate fingers are made wider to increase gate periphery, then output power capability is improved, but electromigration of gate finger metallization occurs
Solution Approach 1:
The gate finger metallization is segmented into multiple sections connected through the gate interconnect structure. This segmentation reduces the current density in any single continuous metallization path, thereby reducing electromigration effects while maintaining the total gate width for high output power
3Power
If conventional transistor design is used to increase gate periphery, then output power is improved, but phase differences in signal propagation increase
Solution Approach 1:
The gate finger is divided into multiple segments along its length, with each segment connected to the gate interconnect at different positions. This segmentation reduces the effective electrical length of each gate segment, thereby reducing phase differences in signal propagation while maintaining the total gate periphery for high output power capability
Solution Approach 2:
The gate interconnect is positioned at multiple heights above the semiconductor structure, creating a three-dimensional interconnect architecture. This vertical dimensionality allows for optimized signal paths that reduce phase differences while maintaining large horizontal gate periphery for power handling
Data Source
AI summary
A transistor device includes a gate finger and a drain finger extending on a semiconductor structure, a gate bond pad coupled to the gate finger, and a drain bond pad coupled to the drain finger. The gate bond pad extends on the gate finger and the drain finger.