RF Passive Network Resonance for Third Harmonic Rejection
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Solution Overview
Problem
Radio-frequency amplifier circuitry in wireless communications devices can produce harmonic leakage, leading to undesired spurious emissions at the antenna, which is not effectively addressed by conventional techniques.
Innovation Solution
A passive network is integrated with a radio-frequency amplifier, comprising a primary coil, a secondary coil, and a harmonic rejection component, such as a capacitor, configured to reject third harmonic signals by resonating at specific frequencies, thereby mitigating harmonic leakage without degrading second harmonic rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional techniques are used to address harmonic leakage, then second harmonic rejection is maintained, but third harmonic distortion is not effectively reduced
Solution Approach 1:
The patent applies local quality by making different parts of the passive network have different properties: the primary coil is configured to reject second harmonic signals while the secondary coil is configured to reject third harmonic signals. This allows each coil to specialize in rejecting specific harmonic frequencies, thereby reducing third harmonic distortion without compromising second harmonic rejection performance.
Solution Approach 2:
The passive network is segmented into functionally distinct primary and secondary coils with different configurations and coupling characteristics. The primary coil handles even harmonic rejection while the secondary coil handles odd harmonic rejection, dividing the harmonic rejection task into separate functional segments that can be optimized independently.
2Object-affected harmful factors
If a passive network with primary and secondary coils is used, then both second and third harmonic rejection are achieved, but device complexity increases
Solution Approach 1:
The patent merges the harmonic rejection function with the existing impedance matching network by integrating the primary and secondary coils into the passive network that already connects the power amplifier to the antenna. This combination allows the network to perform both impedance matching and harmonic rejection functions simultaneously, reducing overall device complexity compared to adding separate harmonic rejection circuits.
Solution Approach 2:
The passive network is designed to serve multiple functions: impedance matching between the power amplifier and antenna, second harmonic rejection through the primary coil, and third harmonic rejection through the secondary coil. This multi-functionality eliminates the need for separate circuits for each function, thereby reducing device complexity.
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 reduces third harmonic distortion while maintaining second harmonic rejection, thus improving signal quality and compliance with emission spectrum criteria.
Implementation Method 1
a secondary coil magnetically coupled to the primary coil
Implementation Method 2
the harmonic rejection component is configured to operate as an open circuit at a first frequency and is further configured to resonate with a portion of the secondary coil at a second frequency different than the first frequency
Data Source
AI summary
Wireless circuitry is provided that includes a radio-frequency amplifier and a passive network coupled to the radio-frequency amplifier. The passive network includes a primary coil, a secondary coil magnetically coupled to the primary coil, and a harmonic rejection component coupled between the primary coil and the secondary coil and configured to reject harmonic signals produced by the radio-frequency amplifier. The harmonic rejection component can be a capacitor. The harmonic rejection component can be configured to operate as an open circuit at a first frequency and can further be configured to resonate with a portion of the secondary coil at a second frequency different than the first frequency.