RF Switch Circuit Topology for Even Voltage Across Stacked Switches
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Solution Overview
Problem
Existing radio frequency switch circuits face issues with uneven voltage allocation due to parasitic capacitance, leading to potential damage from high-voltage inputs, especially for switch devices closer to the signal input/output, which affects power tolerance and reliability.
Innovation Solution
The solution involves connecting capacitors with different capacitance values in parallel to switch devices to equalize voltage distribution, ensuring each switch device receives a voltage below its breakdown voltage, thereby improving power tolerance and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple switch devices are stacked in series to handle high-power signals, then the voltage breakdown capability is improved, but the voltage distribution becomes uneven due to parasitic capacitance, causing higher voltage on switch devices closer to the signal input
Solution Approach 1:
The patent introduces first capacitors with different capacitance values at different positions in the signal path. Specifically, switch devices closer to the signal input are paired with larger capacitance first capacitors, while those farther away use smaller capacitance first capacitors. This local differentiation compensates for the position-dependent voltage imbalance caused by parasitic capacitance, ensuring uniform voltage distribution across all switch devices.
Solution Approach 2:
The patent changes the capacitance parameter of the first capacitors based on their position in the signal path. By adjusting the capacitance values according to the specific electrical characteristics at different locations, the system optimizes voltage distribution. The capacitance values are specifically designed to counterbalance the cumulative effect of parasitic capacitances upstream, transforming the uneven voltage distribution into a uniform one.
2Reliability
If first capacitors with different capacitance values are added to equalize voltage distribution, then the power tolerance is improved, but the circuit layout area increases
Solution Approach 1:
The patent combines the function of voltage equalization with the existing parasitic capacitance structure. Instead of adding separate compensation capacitors that would increase layout area, the first capacitors are integrated into the existing circuit topology, sharing the same physical space and structural framework. This merging approach achieves voltage equalization without proportionally increasing the overall circuit footprint.
Solution Approach 2:
The patent applies first capacitors selectively at specific positions where they are most needed for voltage equalization, rather than uniformly across all switch devices. This localized application optimizes the layout by placing components only where necessary to correct voltage imbalances, minimizing the total circuit layout area while still achieving the desired power tolerance improvement.
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 enhances voltage uniformity across switch devices, increasing the maximum power tolerance and reducing the risk of circuit damage while minimizing circuit layout area.
Implementation Method 1
First capacitors with different capacitance values are connected in parallel to two ends of a switch device, so that a voltage allocated to each switch device on the radio frequency switch circuit is less than a breakdown voltage of the switch device
Data Source
AI summary
This disclosure provides a radio frequency switch circuit and apparatus, and a terminal. The radio frequency switch circuit includes at least one radio frequency signal channel. The radio frequency signal channel includes a signal input end, a signal output end, and a parallel branch. The parallel branch includes a plurality of switch devices and a plurality of first capacitors. First electrodes and second electrodes of the plurality of switch devices are sequentially connected. A first electrode of a 1st switch device is connected to the signal input end or the signal output end. A second electrode of a last switch device is grounded. The switch devices are divided into a plurality of switch device groups. The switch device group includes at least one switch device.