Embedded RF Voltage Sensing in Stacked Switch Transistors
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Solution Overview
Problem
The unequal distribution of high voltage across RF switch cells due to parasitic elements affects the linearity and performance of RF switches, particularly in antenna aperture switches, leading to earlier device failure and suboptimal radiation performance.
Innovation Solution
A voltage sensing circuit is embedded in the stacked transistors of RF antenna aperture switches to measure the RF voltage swing across individual transistors without influencing the circuit's operation, providing a DC readout for monitoring and adjusting the voltage distribution, thereby ensuring equal voltage distribution across all cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple RF cells are coupled together to handle high voltage, then the voltage breakdown limit is exceeded, but unequal voltage distribution occurs due to parasitic elements
Solution Approach 1:
The patent divides the high voltage handling function into multiple RF cells connected in series, where each cell handles a fraction of the total voltage. This segmentation allows the system to withstand high voltage while keeping individual transistor stress within safe limits, though parasitic elements cause non-uniform voltage distribution across the segmented cells
Solution Approach 2:
The patent introduces a sensing circuit that measures the actual voltage across each RF cell and feeds this information back to a control system. The control system adjusts the biasing or switching parameters of individual cells to compensate for unequal voltage distribution caused by parasitic elements, thereby achieving uniform voltage sharing across all cells
2Manufacturing precision
If voltage sensing circuit is embedded in stacked transistors, then voltage distribution can be monitored and adjusted, but device complexity increases
Solution Approach 1:
The patent merges the voltage sensing function with the existing RF switch structure by embedding sensing circuits within the stacked transistor configuration. The sensing circuits share common nodes and control pathways with the RF cells, allowing voltage monitoring without adding completely separate measurement systems
Solution Approach 2:
The sensing circuits are designed to serve multiple functions: they monitor voltage across RF cells, provide feedback for voltage balancing, and can potentially detect fault conditions. This multi-functionality reduces the need for dedicated circuits for each purpose, thereby limiting the increase in overall device complexity
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
The solution allows for precise measurement and adjustment of voltage distribution, enhancing the linearity and reliability of RF switches by minimizing the impact of parasitic elements and preventing premature device failure.
Implementation Method 1
a first filter having an input coupled to the first current node of the first transistor and an output configured for providing a DC voltage corresponding to the RF power present at the first internal switch node
Data Source
AI summary
An RF switch includes series-coupled RF switch cells coupled between an RF input and ground, a transistor including a first current node coupled to a first load resistor, a second current node coupled to ground, and a control node coupled to an internal switch node, and a filter having an input coupled to the first current node of the first transistor and an output for providing a DC voltage corresponding to the RF power present at the internal switch node.