Parallel Notch Band-Pass Filter for 5G Frequency Isolation
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Solution Overview
Problem
Conventional band pass filters in mobile communication devices fail to adequately isolate 5G frequency bands above 3 GHz due to insufficient frequency margins and interference from neighboring bands, as well as electromagnetic interference from devices operating outside traditional telecommunication frequency ranges.
Innovation Solution
A band pass filter device comprising a first and second filter circuit connected in parallel, where the first circuit includes a notch filter and the second circuit includes a notch filter and a phase shifter, providing steep roll-offs at the lower and upper cutoff frequencies to prevent interference, with low insertion loss within the passband and high insertion loss in adjacent stopbands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional band pass filters are used to isolate 5G frequency bands, then the filter structure is simple, but the frequency isolation is insufficient and interference from neighboring bands occurs
Solution Approach 1:
The filter is divided into multiple resonator units (first resonator unit, second resonator unit, third resonator unit) that work together to provide both the desired passband and the required stopband rejection. Each resonator unit contributes specific frequency rejection characteristics that collectively achieve the target isolation performance.
Solution Approach 2:
Multiple resonator units are combined in a unified filter structure where their frequency responses are merged to achieve the composite transfer function. The resonators are coupled through shared electrical nodes, allowing their individual rejection notches to combine and form the required stopbands while maintaining a common passband.
2Productivity
If the frequency separation between bands is narrowed to maximize bandwidth, then the available bandwidth increases, but the filtering precision requirements become more stringent
Solution Approach 1:
Different resonator units are designed with specific local characteristics tailored to reject particular frequency ranges. The first resonator unit targets lower frequency interference, the second targets the upper band edge, and the third targets higher frequency interference, allowing precise control over the filter response at different frequency points.
Solution Approach 2:
The resonators are designed with specific inductance and capacitance values that determine their resonant frequencies and rejection characteristics. By carefully selecting these electrical parameters, the filter achieves precise frequency selectivity with steep roll-off characteristics, enabling narrow band separation while maintaining high filtering precision.
3Reliability
If band pass filters are designed with steep roll-off characteristics, then the frequency isolation improves, but the insertion loss in the passband may increase
Solution Approach 1:
The filter utilizes dynamic coupling between resonators where the coupling strength varies with frequency. At the passband center frequency, the coupling is optimized for minimum insertion loss, while at frequencies approaching the stopbands, the coupling creates the necessary steep roll-off. This dynamic behavior allows the filter to maintain low loss in the passband while achieving sharp transitions.
Solution Approach 2:
The filter design uses multiple resonator units with similar structural configurations but different electrical parameters. This copying approach allows the successful design of one resonator unit to be replicated and adapted for other frequency ranges, ensuring consistent performance characteristics while achieving the required steep roll-off through proper parameter scaling.
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 isolates 5G frequency bands by providing steep roll-offs at the cutoff frequencies, minimizing interference from neighboring bands and ensuring low signal attenuation within the desired frequency range while maintaining high signal blocking in adjacent bands, thus preventing interference from other frequency bands.
Implementation Method 1
a first resonator unit coupled to a first node and a second node, and providing a first frequency rejection above a first frequency; a second resonator unit coupled to the first node and the second node, and providing a second frequency rejection below a second frequency
Implementation Method 2
providing a passband between the lower cutoff frequency and the upper cutoff frequency, and providing frequency rejection in a first stopband above the upper cutoff frequency and in a second stopband below the lower cutoff frequency
Data Source
AI summary
A filter device provides a wideband passband of a communication device for a RF signal. The filter device includes a first filter circuit in parallel with a second filter circuit. The first filter circuit includes a first notch filter, and has a first notch. The second filter circuit includes a second notch filter in series with a reversal circuit for phase shifting the RF signal filtered by the second notch filter, the second filter circuit having a second notch. The first and second filter circuits form a band pass filter having a passband between a lower cutoff frequency defined by the second notch and an upper cutoff frequency defined by the first notch. The band pass filter provides low insertion loss in the passband, and high insertion loss in an adjacent lower stopband below the lower cutoff frequency and in an adjacent upper stopband above the upper cutoff frequency.