Series-Parallel RF Switching Circuit Balancing Speed and Linearity
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Solution Overview
Problem
Existing radio frequency switch circuits face challenges in reducing switching time while maintaining performance indices like power handling capacity, isolation, and linearity without increasing cost or complexity.
Innovation Solution
A fast-switching radio frequency switch circuit design incorporating series and parallel switch branches with optimized transistor structures and capacitors to improve linearity and reduce switching time, featuring a switching transistor stack with body bias resistors and gate bias resistors, and additional capacitors to enhance signal isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If series-parallel radio frequency switch circuit is used, then switching time is reduced and chip area is small, but linearity deteriorates
Solution Approach 1:
The switch branch is segmented into multiple stacked switching transistors (first, second, third switching transistors) connected in series, where each transistor contributes to the overall switching function. This segmentation allows the circuit to achieve fast switching while maintaining good linearity through the distributed structure, resolving the contradiction between switching speed and linearity.
Solution Approach 2:
Different parts of the circuit are assigned different functions: the series connection of switching transistors provides fast switching action, while the parallel capacitor provides linearity improvement by maintaining voltage stability. This local differentiation of functions allows simultaneous achievement of fast switching and good linearity.
2Manufacturing precision
If relative negative voltage radio frequency switch circuit is used, then linearity is improved, but chip area increases and switching time increases
Solution Approach 1:
The complex negative voltage generation circuit and series capacitor structure are extracted and replaced with a simplified approach using parallel capacitors connected to ground. This extraction removes the problematic elements causing long switching time and large chip area while preserving the linearity improvement function through the parallel capacitor voltage stabilization effect.
3Manufacturing precision
If constant negative voltage radio frequency switch circuit is used, then linearity is significantly improved and switching time is reduced, but device complexity increases and power consumption increases
Solution Approach 1:
The expensive and complex constant negative voltage generation circuit (charge pump driven by fully differential ring oscillator) is replaced with simple parallel capacitors connected to ground. These simple capacitive elements provide the necessary linearity improvement without the high complexity and power consumption of the constant negative voltage circuit, effectively using simpler components to achieve the desired performance.
Data Source
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AI summary
Disclosed in the present invention are a fast-switching radio frequency switch circuit, a chip and an electronic device thereof. The radio frequency switch circuit comprises a series switch branch and a parallel switch branch of at least one transmission path, and a series switch branch and a parallel switch branch of at least one reception path. In said transmission path, two ends of the series switch branch are respectively connected to a transmission end and an antenna end, and two ends of the parallel switch branch are respectively connected to the transmission end and a grounding potential end. In said reception path, two ends of the series switch branch are respectively connected to a reception end and the antenna end, and two ends of the parallel switch branch are respectively connected to the reception end and the grounding potential end. By means of an optimized structural design, the radio frequency switch circuit achieves fast switching of operating modes of radio frequency front-end systems while ensuring performance indexes such as power handling capacity and linearity and not increasing the cost, thus improving the transmission rate of communication systems.