Transformer-Based RF Switch for High Linearity and Low Insertion Loss
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Solution Overview
Problem
RF switches in TDD systems face challenges in achieving high isolation, linearity, and low insertion loss due to the use of CMOS transistors, which result in non-linearity and significant signal loss.
Innovation Solution
The RF switch employs transformers for switching operations instead of transistors, incorporating a capacitor switch array for impedance matching, allowing for high isolation, linearity, and low insertion loss by connecting the transformers in series and parallel configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If CMOS transistors are used for RF switching, then the switch can be integrated on a chip, but non-linearity and high insertion loss occur
Solution Approach 1:
The patent replaces the electronic transistor-based switching mechanism with a transformer-based electromagnetic coupling mechanism. The transformer uses magnetic field coupling between primary and secondary windings to transfer signals, eliminating the non-linear characteristics of CMOS transistors while maintaining chip integrability through planar transformer structures.
Solution Approach 2:
The patent changes the fundamental operating parameters of the switching mechanism by using transformer turns ratios and magnetic coupling coefficients instead of transistor gate voltages and channel conductances. This parameter transformation enables linear signal transfer with controlled impedance matching, resolving the linearity issue while preserving integration benefits.
2Ease of manufacture
If CMOS transistors are used for RF switching, then chip integration is achieved, but insertion loss increases
Solution Approach 1:
The transformer-based switching mechanism replaces resistive transistor channels with inductive magnetic coupling paths. This substitution eliminates the ohmic losses inherent in transistor operation, significantly reducing insertion loss while maintaining the ability to integrate the switch on a chip using planar transformer geometries.
Solution Approach 2:
The patent merges the switching function with the signal transfer function by using the transformer's magnetic coupling to simultaneously achieve signal isolation during switching and efficient energy transfer during conduction. This integration of functions reduces the number of separate components and minimizes cumulative losses.
3Reliability
If transformers are used for switching, then linearity and low insertion loss are achieved, but device complexity increases
Solution Approach 1:
The transformer structure performs multiple functions simultaneously: it provides signal transfer, impedance matching, and isolation in a single component. This multi-functionality reduces the overall device complexity by eliminating the need for separate baluns, inductors, and switches that would otherwise be required in a transistor-based design.
Solution Approach 2:
The patent employs composite planar transformer structures that integrate multiple functional elements (primary winding, secondary winding, magnetic core, and capacitive elements) into a unified planar geometry. This composite approach maintains chip compatibility while achieving the desired linearity and low loss performance.
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 effectively minimizes non-linearity and insertion loss while maintaining high isolation, reducing the need for separate baluns and inductors, thereby optimizing performance and reducing manufacturing costs.
Implementation Method 1
a transmitting end transformer having a primary side connected to a transmitting end and a secondary side connected to an antenna
Data Source
AI summary
A radio frequency (RF) switch with a transformer and a switching method thereof are provided. The RF switch includes a transmitting end transformer having a primary side connected to a transmitting end and a secondary side connected to an antenna; and a receiving end transformer having a primary side connected to the antenna and a secondary side connected to a receiving end. In a transmission mode, the transmitting end transformer is tuned on, and, in a reception mode, the receiving end transformer is turned on. Accordingly, since switching is performed based on transformers rather than transistors connected in series, the RS switch, which can achieve high linearity and low insertion loss as well as high isolation, can be implemented.