RF Switch Dynamic Body Coupling for IMD Reduction
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Solution Overview
Problem
Radio-frequency (RF) switches face challenges in achieving optimal switching performance due to issues like high insertion loss, intermodulation distortion, and power handling limitations, particularly in multi-band and multi-mode wireless communication systems, where existing designs struggle to maintain linearity and reduce interference.
Innovation Solution
The implementation of a radio-frequency switch using a series connection of field-effect transistors (FETs) with a compensation network that includes gate-coupling and body-coupling circuits, utilizing silicon-on-insulator (SOI) technology to reduce voltage swings and improve intermodulation distortion (IMD) performance, and incorporating adjustable resistance circuits to optimize IMD and insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple FETs are connected in series to improve power handling capability, then power handling capability is improved, but voltage swings across each FET become uneven and intermodulation distortion increases
Solution Approach 1:
The patent implements a feedback mechanism where the body of each FET is coupled to the drain of the previous FET through a capacitive divider network. This feedback path monitors the voltage at the drain node and adjusts the body voltage of the next FET accordingly, ensuring uniform voltage distribution across all series-connected FETs and reducing intermodulation distortion.
Solution Approach 2:
The patent changes the electrical parameters by introducing body voltage control through capacitive dividers. By dynamically adjusting the body voltage of each FET based on the drain voltage of the previous stage, the system optimizes the voltage distribution parameters to achieve uniform voltage swings across all FETs, thereby reducing intermodulation distortion while maintaining high power handling capability.
2Object-generated harmful factors
If body voltage is controlled to reduce voltage swings and improve linearity, then intermodulation distortion is reduced, but device complexity increases
Solution Approach 1:
The patent merges the body bias control function with the existing drain node structure by coupling the body of each FET to the drain of the previous FET through capacitive dividers. This integration eliminates the need for separate body bias control circuits, reducing device complexity while achieving uniform voltage distribution and reduced intermodulation distortion.
Solution Approach 2:
The system implements self-service by using the drain voltage of each FET to automatically control the body voltage of the next FET through the capacitive divider network. This self-regulating mechanism ensures uniform voltage distribution across all FETs without requiring external control circuits, thereby reducing device complexity while improving linearity and reducing intermodulation distortion.
Data Source
AI summary
Radio-frequency (RF) switch circuits are disclosed including at least one first field-effect transistor (FET) disposed between first and second nodes, each of the at least one first FET having a respective body and gate. The RF switch circuit may include a coupling circuit that couples the respective body and gate of the at least one first FET, the coupling circuit configured to be switchable between a resistive-coupling mode and a body-floating mode, as well as an adjustable-resistance circuit connected to either or both of the respective gate and body of the at least one FET, the adjustable-resistance circuit including a resistor in parallel with a bypass switch.