BAW Filter Circuit With Resonant Notch for Second Harmonic Suppression
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Solution Overview
Problem
Bulk acoustic wave (BAW) filters in wireless communication devices generate undesirable second harmonics, which traditional techniques such as apodization and border rings fail to adequately suppress, posing challenges for meeting strict wireless communication regulations.
Innovation Solution
Incorporating a resonant tank circuit with magnetic coupling components, such as inductors, to selectively attenuate undesired high-frequency signals, including second harmonics, by tuning the circuit to provide a frequency notch and improve suppression performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional techniques such as apodization and border rings are used to minimize H2 self-generation, then manufacturing complexity is reduced, but H2 suppression performance is insufficient within power amplifier multiplexer networks
Solution Approach 1:
A resonant tank circuit comprising a capacitor and an inductor is introduced as an intermediary component between the BAW filter and the power amplifier multiplexer network. This resonant tank circuit is specifically tuned to create a frequency notch at the second harmonic frequency, effectively suppressing H2 self-generation without requiring modifications to the BAW filter structure itself. The resonant tank circuit acts as a mediator that addresses the H2 suppression issue while maintaining manufacturing simplicity.
Solution Approach 2:
The resonant tank circuit is designed with specific parameter values for the capacitor and inductor to achieve resonance at the second harmonic frequency. By adjusting the capacitance and inductance values, the circuit creates a frequency-selective notch that targets H2 suppression. This parameter-based approach allows for flexible tuning and optimization of suppression performance without changing the fundamental structure or manufacturing process of the BAW filter.
2Object-generated harmful factors
If a resonant tank circuit with magnetic coupling components is added to suppress second harmonics, then H2 suppression performance improves by at least 8 to 10 dB, but device complexity increases
Solution Approach 1:
The resonant tank circuit is integrated with the existing power amplifier multiplexer network by electrically connecting the inductor to the conductive path between the BAW filter output and the multiplexer input. This merging approach allows the suppression function to be added to the existing circuit architecture without creating completely separate systems. The resonant tank circuit shares common ground references and signal paths with the multiplexer network, reducing overall system complexity compared to fully independent suppression circuits.
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 suppresses second harmonics by at least 8 to 10 dB compared to traditional methods, enhancing the performance of wireless communication circuitry while minimizing space requirements.
Implementation Method 1
a resonant tank circuit including a capacitor and an inductor magnetically coupled to the first inductor
Implementation Method 2
The resonant circuit is tuned to suppress an undesired high-frequency signal passing through the wireless communication circuitry
Data Source
AI summary
Wireless communication circuitry is disclosed. The wireless communication circuitry includes an antenna terminal and an electrically conductive path between a first port terminal and the antenna terminal through a second port terminal. Also included is a bulk acoustic wave filter configured to filter and pass a desired radio frequency signal between the first port terminal and the second port terminal. Further included is a first magnetic coupling component that is electrically connected to the electrically conductive path and a resonant circuit made up of a capacitor and a second magnetic coupling component that is magnetically coupled to the first magnetic coupling component. The resonant circuit is tuned to suppress an undesired desired radio frequency signal that in some embodiments is the second harmonic of the desired radio frequency signal.