High-Frequency Front End Circuit with Variable LC and Resonator Filters
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Solution Overview
Problem
Wireless communication systems utilizing TV white space face challenges due to varying channels and narrow frequency band widths, leading to noise interference issues.
Innovation Solution
A high-frequency front end circuit is designed with a combination of fixed and variable filters to selectively attenuate unnecessary waves, using a frequency fixed-type LC filter and frequency variable-type elastic wave resonator filters to ensure effective signal passage and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed filter configuration is used, then the filter structure is simple, but it cannot effectively attenuate noise in varying communication channels with narrow bandwidth
Solution Approach 1:
The patent applies dynamics by making the filter configuration variable rather than fixed. The filter's frequency characteristics can be dynamically adjusted to match different communication channels, allowing the system to adapt to varying channels while maintaining effective noise attenuation. This resolves the contradiction by enabling the filter to change its properties based on the specific channel being used.
Solution Approach 2:
The patent changes the filter parameters (frequency, bandwidth) to match different communication channels. By adjusting these parameters dynamically, the filter can effectively attenuate noise in varying channels with narrow bandwidth without requiring a completely different filter structure for each channel, thus balancing adaptability with manageable complexity.
2Productivity
If narrow frequency bands are used for communication channels, then more channels can fit in the TV white space, but noise interference increases due to proximity of channels
Solution Approach 1:
The patent applies local quality by providing different attenuation characteristics for different frequency regions. The filter is designed to provide stronger attenuation specifically in the narrow bands between adjacent communication channels, while maintaining adequate performance within each channel band. This localized approach to noise suppression allows more channels to coexist without excessive interference.
Solution Approach 2:
The dynamic filter configuration allows the system to adjust its attenuation characteristics based on which channels are currently in use. When channels are densely packed, the filter can be configured to provide enhanced attenuation in the narrow gaps between them, effectively reducing noise interference while maintaining the ability to support multiple channels.
3Object-affected harmful factors
If variable filters are added to handle varying channels, then noise attenuation improves, but the circuit complexity increases
Solution Approach 1:
The patent implements a variable filter that can serve multiple communication channels with a single device. This multi-functional filter replaces what would otherwise require multiple separate fixed filters, one for each channel. By making one filter variable rather than adding multiple fixed filters, the system achieves improved noise attenuation while actually reducing overall circuit 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 circuit effectively transmits high-frequency signals in the usage channel while attenuating unnecessary waves, reducing noise interference and maintaining low loss, even in systems with varying vacant and usage channels and narrow frequency bands.
Implementation Method 1
a fixed filter and a variable filter. The fixed filter attenuates a high-frequency signal outside the specific frequency band that is used in the system
Implementation Method 2
The variable filter attenuates a high-frequency signal of an unnecessary wave in the specific frequency band, which varies depending on the usage channel
Data Source
AI summary
A high-frequency front end circuit includes a frequency fixed filter and frequency variable LC filters, and these are connected in series in a signal transmission path. The frequency fixed filter transmits high-frequency signals in a frequency band of a communication band and attenuates high-frequency signals outside the frequency band of the communication band. One of the frequency variable LC filters is an LC filter and attenuates unnecessary wave frequencies in the frequency band of the communication band. Another one of the frequency variable filters is a resonator filter that passes high-frequency signals in a frequency band of a selected channel and attenuates high-frequency signals in frequency bands of adjacent communication channels of the selected channel.