SOI RF Switch Coupling Circuits for Low IMD and Insertion Loss
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Solution Overview
Problem
Radio-frequency (RF) switches face challenges in achieving high linearity, low insertion loss, and reduced intermodulation distortion (IMD) due to substrate parasitics and process limitations, which affect their performance in multi-band and multi-mode wireless communication systems.
Innovation Solution
The implementation of field-effect transistor (FET)-based RF switch circuits with innovative biasing and coupling configurations, including non-linear capacitors, RC circuits, and frequency-tuned LC circuits, to compensate for non-linearity effects and improve IMD performance, while minimizing additional area and process complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional RF switch designs are used, then device simplicity is maintained, but non-linearity effects and intermodulation distortion increase
Solution Approach 1:
A coupling circuit is introduced as an intermediary component between the FET and ground. This coupling circuit includes a capacitor connected between the source/drain and gate, and a resistor connected between the gate and ground, forming a mediator that compensates for non-linearity effects without requiring fundamental changes to the switch architecture
Solution Approach 2:
The invention changes the electrical parameters by introducing specific capacitor and resistor values in the coupling circuit. The capacitor value and resistor value are selected to provide optimal compensation for non-linearity effects, transforming the static FET operation into a dynamically compensated system that reduces intermodulation distortion
2Reliability
If biasing and coupling circuits are added to improve switching performance, then linearity and IMD performance are enhanced, but insertion loss may increase
Solution Approach 1:
The resistor value in the coupling circuit is carefully selected to provide optimal compensation while minimizing power loss. By adjusting this parameter, the system achieves a balance where non-linearity compensation is effective but the additional energy loss remains minimal, preserving low insertion loss characteristics
Solution Approach 2:
The coupling circuit provides partial compensation for non-linearity effects rather than attempting complete elimination. This partial action approach achieves sufficient improvement in linearity and IMD performance without over-compensating, which would otherwise increase circuit loss and reduce efficiency
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
These configurations significantly reduce non-linearity effects, enhance IMD performance, and maintain low insertion loss, enabling improved switching performance in RF switches for multi-band and multi-mode wireless communication systems.
Implementation Method 1
a capacitor connected between the source or drain and the gate
Implementation Method 2
a resistor connected between the gate and a reference node
Data Source
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AI summary
Radio-frequency (RF) switch circuits are disclosed providing improved switching performance. An RF switch system typically includes a plurality of field- effect transistors (FETs) connected in series between first and second nodes, with each FET having a gate, a source, a drain and a body. Disclosed are, among others, various examples of circuits that couple different portions of a FET and/or different FETs to yield desirable performance improvements for RF switch systems. In some embodiments, one or more features of a given example can provide such performance improvements. In some embodiments, features from different examples can be combined to yield such performance improvements.