Current-Balun Bridge Filter for Wideband Low-Error RF Filtering
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Solution Overview
Problem
Existing wireless transceivers face challenges in achieving wide bandwidths and superior out-of-band attenuation necessary for 5G and 6G technologies, with lattice filters often producing magnitude and phase errors that exceed operational parameters.
Innovation Solution
The implementation of a bridge filter with a current balun and a filter core, utilizing galvanic coupling and acoustic wave resonators, provides a wider passband and greater out-of-band attenuation, reducing signal errors through equal current flow in balanced paths and compensating with additional inductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a lattice filter is used to achieve filtering functionality, then the filter provides frequency selection capability, but magnitude and phase errors exceed operational parameters
Solution Approach 1:
A current balun is introduced as an intermediary component between the single-ended input/output and the differential bridge filter core. This balun converts single-ended signals to differential signals and ensures equal current flow in both paths, eliminating the magnitude and phase errors that would otherwise exceed operational parameters.
Solution Approach 2:
The patent changes the signaling type from single-ended to differential by incorporating a current balun. This parameter change transforms the operating mode of the filter, enabling it to achieve lower magnitude and phase errors while maintaining compliance with operational parameters.
2Speed
If a bridge filter with current balun is used to achieve wider passband, then the bandwidth increases, but the device complexity increases
Solution Approach 1:
The filter circuit is segmented into distinct functional modules: a current balun section for signal conversion and a bridge filter core section for frequency selection. This segmentation allows the wide bandwidth capability to be achieved through the balun's differential signaling while keeping the filter core design relatively simple and modular.
Solution Approach 2:
The current balun serves multiple functions simultaneously: it converts single-ended to differential signaling, ensures equal current distribution in both paths, and provides impedance matching. This multi-functionality achieves wide bandwidth without proportionally increasing 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 described bridge filter achieves lower magnitude and phase errors, widening the passband and increasing out-of-band suppression, meeting the requirements of 5G and future 6G technologies while minimizing signal distortions.
Implementation Method 1
A first inductor is galvanically coupled, at least within the current balun, between the first port and a terminal of the filter core. A second inductor is galvanically coupled, at least within the current balun, between a ground and another terminal of the filter core.
Implementation Method 2
The filter core can be constructed using a lattice filter architecture with multiple resonators, and each resonator may include one or more acoustic wave resonators.
Data Source
AI summary
An apparatus is disclosed for bridge filters. In example aspects, the apparatus includes a filter circuit with a current balun and a filter core. The current balun includes a first terminal coupled to a first port of the filter circuit, a second terminal, a third terminal, and a fourth terminal. The current balun also includes a first inductor galvanically coupled between the first terminal and the second terminal. The current balun further includes a second inductor galvanically coupled between the third terminal and the fourth terminal. The filter core is coupled between the current balun and a second port of the filter circuit. The filter core is galvanically coupled to the second terminal of the current balun and to the fourth terminal of the current balun.