Bias Circuit for High-Voltage RF Switch Voltage Distribution
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Solution Overview
Problem
High-voltage RF switches with stacked transistors face unequal voltage distribution due to parasitic capacitances and leakage currents, leading to reduced voltage handling and performance issues, such as earlier breakdown and distortion.
Innovation Solution
Implementing a biasing arrangement with individually adjustable gate voltages and a defined slope for each transistor in the stack, which counterbalances parasitic capacitances and leakage currents, ensuring equal voltage distribution and improved linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple RF cells are stacked to handle high voltage, then the voltage handling capacity is improved, but unequal voltage distribution occurs due to parasitic elements
Solution Approach 1:
The patent applies different bias voltages to different RF cells in the stack based on their position. Specifically, cells experiencing higher voltage stress due to parasitic effects are given different bias conditions than cells with lower stress, creating local quality variations that compensate for the non-uniform voltage distribution caused by parasitic elements
Solution Approach 2:
The patent changes the bias voltage parameter for individual RF cells to counterbalance the unequal voltage distribution. By adjusting the gate bias voltage of each cell according to its position in the stack, the patent compensates for parasitic effects and achieves more uniform voltage distribution across all cells
2Strength
If multiple RF cells are stacked to handle high voltage, then the voltage handling capacity is improved, but linearity and performance characteristics deteriorate
Solution Approach 1:
The patent applies position-dependent bias voltages to different RF cells to maintain consistent performance characteristics. By locally adjusting the bias conditions based on each cell's position and its specific parasitic characteristics, the patent ensures that all cells operate in their optimal region, preserving linearity and performance
Solution Approach 2:
The patent preemptively applies compensating bias voltages to RF cells before they experience performance degradation. By anticipating the unequal voltage distribution caused by parasitic elements and applying counteracting bias in advance, the patent prevents linearity deterioration and maintains reliable performance characteristics
3Stability of the object's composition
If individual bias voltages are applied to each RF cell, then voltage distribution equality is improved, but device complexity increases
Solution Approach 1:
The patent divides the bias control into separate segments for each RF cell. By providing individual bias voltage control for each cell rather than a single common bias, the patent enables precise compensation for parasitic effects in each position, achieving equal voltage distribution across the stack
Solution Approach 2:
The patent introduces bias voltage as an intermediary parameter to mediate the unequal voltage distribution caused by parasitic elements. By using adjustable bias voltages on the gate terminals of each RF cell, the patent creates a control mechanism that compensates for the non-uniform voltage stress and achieves balanced operation
Data Source
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Figure 3(a)~4(b)
Figure 5(a)~5(b)
AI summary
An RF switch includes series-coupled RF switch cells coupled between an RF input and ground, each RF switch cell having an input, and a biasing network having outputs for individually biasing each of the RF switch cell inputs to a distinct bias voltage based upon a rank number of the RF switch cell