RF Front-End Variable Filtering for Spurious Wave Suppression
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Solution Overview
Problem
In wireless communication systems using TV white spaces, spurious waves caused by varying television broadcasting frequencies are not effectively suppressed by fixed filters, leading to interference and degradation of receiving sensitivity.
Innovation Solution
A high-frequency front end circuit with a variable filter and RFIC that identifies and attenuates interference waves in neighboring frequency domains, using a combination of elastic wave and LC filters to maintain receiving sensitivity even when communication channel frequencies change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed filters are used to suppress spurious waves, then the filter structure is simple and cost-effective, but the spurious waves cannot be effectively suppressed when communication channel frequencies vary
Solution Approach 1:
The patent employs a variable filter with adjustable cutoff frequency that can dynamically adapt to different communication channel frequencies. The filter's cutoff frequency is set to be variable within a range that covers potential spurious wave frequencies, allowing the system to maintain effective suppression regardless of frequency variations in the communication channels.
2Adaptability or versatility
If a variable filter is introduced to handle frequency variations, then adaptability to frequency changes is improved, but the device complexity increases
Solution Approach 1:
The patent changes the parameter of the filter's cutoff frequency from fixed to variable, allowing the same filter structure to handle multiple frequency scenarios. This parameter change enables the filter to adapt to different communication channel frequencies without requiring multiple separate filters, thus managing complexity while improving adaptability.
3Reliability
If the filter cutoff frequency is set low to suppress spurious waves, then spurious wave suppression is effective, but the receiving sensitivity in the communication channel is degraded
Solution Approach 1:
The patent dynamically adjusts the filter's cutoff frequency based on the actual communication channel frequency and potential spurious wave frequencies. By setting the cutoff frequency appropriately relative to the communication channel frequency, the filter suppresses spurious waves while preserving the desired signal, thus maintaining receiving sensitivity.
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 spurious waves and maintains receiving sensitivity by dynamically adjusting filter characteristics based on interference detection, ensuring reliable wireless communication even with varying channel frequencies.
Implementation Method 1
a filter that attenuates a high-frequency signal outside the specific frequency band
Implementation Method 2
a variable filter that attenuates a high-frequency signal in at least one used communication channel, among used communication channels that are used by the system and that causes an interference wave occurring in a neighbor frequency domain including the wireless communication channel
Data Source
AI summary
A high-frequency front end circuit includes a fixed frequency filter and an interference-wave suppression variable filter. The fixed frequency filter attenuates a high-frequency signal outside a specific frequency band. The interference-wave suppression variable filter attenuates a high-frequency signal in at least one used communication channel, among used communication channels that are used by a system and that causes an interference wave occurring in a neighbor frequency domain including a wireless communication channel.