Harmonic-Rejected Antenna Switch Using Differential Topology
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Solution Overview
Problem
Conventional radio frequency antenna switches generate harmonic frequencies and are susceptible to electromagnetic discharge damage due to on-chip capacitors being grounded, which limits their effectiveness.
Innovation Solution
A harmonic-rejected multiport radio frequency antenna switch design using a set of radio frequency switches with inductors and capacitor arrays, where the capacitor arrays can be configured with fuse elements or control logic to reject harmonic frequencies and prevent electromagnetic discharge damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional LC filters are used to filter out harmonics, then harmonic rejection is improved, but the on-chip capacitor becomes susceptible to electrostatic discharge damage
Solution Approach 1:
The patent introduces an intermediary balanced switch configuration that mediates between the need for harmonic filtering and protection from ESD damage. The differential structure acts as an intermediary mechanism that achieves harmonic rejection through the switching action itself rather than through vulnerable on-chip capacitors, thereby resolving the contradiction between harmonic rejection and ESD susceptibility
Solution Approach 2:
The patent inverts the conventional approach by using a balanced/differential switch topology instead of a single-ended switch with LC filters. This inversion allows the switch itself to provide harmonic rejection through its differential operation, eliminating the need for vulnerable on-chip capacitors and thus resolving the contradiction between harmonic rejection and reliability
2Ease of operation
If series FETs are used in the antenna switch, then switching functionality is achieved, but harmonic frequencies are generated
Solution Approach 1:
The patent segments the single-ended switch into multiple differential pairs, where each pair handles a portion of the switching function. This segmentation allows the harmful harmonic effects to cancel out due to the differential operation, while maintaining the required switching functionality. The segmented approach resolves the contradiction by distributing the switching action across multiple balanced elements
Solution Approach 2:
The patent converts the harmful harmonic generation of FETs into a beneficial effect by using differential operation. The harmonics generated by each FET in the differential pair are equal and opposite, causing them to cancel each other out. This transforms the harmful harmonic generation into a benefit where the same nonlinearity that generates harmonics in single-ended operation now provides harmonic cancellation in differential operation
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
The solution effectively rejects harmonic frequencies and prevents electromagnetic discharge damage, as demonstrated by significant attenuation of harmonics in the frequency response, enhancing the reliability and performance of radio frequency antenna switches.
Implementation Method 1
Conventional inductor-capacitor (LC) filters can be used to filter out harmonics
Implementation Method 2
The conventional state-of-the-art antenna switch consists of a set of series field effect transistors (FETs)
Data Source
AI summary
The exemplary embodiments include a radio frequency antenna switch configured to reject harmonic frequencies. In addition, the harmonic-rejected radio frequencies of the radio frequency antenna switch may be tuned by use of a capacitor array. The capacitor array may be configured with fuse elements or by control logic.