RF Switch Shunt Varactor Asymmetry for H2 and H3 Cancellation
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Solution Overview
Problem
Radio-frequency (RF) switches face challenges in reducing second and third order distortions, which affect their performance and linearity, particularly due to the non-linearities introduced by field-effect transistors.
Innovation Solution
The implementation of an asymmetric anti-series varactor pair in parallel with the shunt arm of the RF switch, configured to reduce both second and third order distortions by controlling the width and geometry of the varactors, allowing for simultaneous cancellation of harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If field-effect transistors are used in the shunt arm of the RF switch, then switching functionality is achieved, but second and third order distortions are generated
Solution Approach 1:
The patent applies asymmetry by using varactors with different widths (first varactor width ≠ second varactor width) in the anti-series configuration. This asymmetric design allows the varactor pair to generate specific harmonic distortions that cancel the second and third order distortions produced by the field-effect transistors, thereby improving linearity while maintaining switching functionality.
Solution Approach 2:
The patent converts the harmful non-linear characteristics of the varactors into a beneficial effect. By carefully selecting different widths for the two varactors in the anti-series pair, the harmful harmonic distortions generated by the varactors are transformed into useful cancellation signals that neutralize the second and third order distortions from the transistors, turning a potential problem into a solution.
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 configuration effectively reduces both second and third order distortions, improving the linearity and performance of RF switches by offsetting intermodulation products generated by the field-effect transistors.
Implementation Method 1
a varactor stack comprising an asymmetric anti-series varactor pair, the varactor stack coupled coupled in parallel to the shunt arm between the series arm and the reference potential node, the varactor stack configured to simultaneously reduce second order distortions and third order distortions generated by the set of field-effect transistors in the shunt arm
Data Source
AI summary
Described herein are switches with asymmetrical anti-series varactor pairs to improve switching performance. The disclosed switches can include asymmetrical varactor pairs to reduce distortions. The asymmetry in the varactor pairs can be associated with geometry of each varactor in the pair. The disclosed switches can stack both symmetrical and asymmetrical varactor pairs. The disclosed switches with asymmetrical anti-series varactor pairs can be configured to improve both H2 and H3 simultaneously.