5G RF Front-End Noise Filter for Spurious Emission Control
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Solution Overview
Problem
RF systems face challenges in maintaining low spurious emissions in overlapping frequency bands, particularly when operating in multiple uplink bands like 5G NR n1 and n65, which can interfere with adjacent downlink bands such as n34, leading to increased noise and reduced coexistence efficiency.
Innovation Solution
A shared duplexer front end architecture with a noise filter circuit, including a switch and notch filter, is configured to selectively enable or disable the noise filter based on the operating uplink band, ensuring spurious emissions in the n34 band are maintained below −50 dBm/MHz by attenuating noise in the passband of the notch filter by at least 10 dBm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a shared duplexer is used for uplink in multiple frequency bands, then device complexity is reduced and spectrum utilization is improved, but spurious emissions increase and coexistence between bands deteriorates
Solution Approach 1:
The patent divides the filtering function into multiple frequency-specific filters (first frequency filter for first uplink band, second frequency filter for second uplink band). Each filter is optimized for its specific band, allowing the system to maintain low spurious emissions in each band while using a shared duplexer architecture.
Solution Approach 2:
The patent introduces frequency filters as intermediary components between the power amplifier and the shared duplexer. These filters act as mediators that selectively pass desired frequency bands while blocking spurious emissions, enabling coexistence between multiple uplink bands and adjacent downlink bands.
2Object-generated harmful factors
If a noise filter is added to reduce spurious emissions, then coexistence between bands is improved, but device complexity and component count increase
Solution Approach 1:
The patent employs switches to dynamically enable or disable specific frequency filters based on the currently active uplink band. This dynamic configuration allows the system to use only the necessary filter for the current operating band, reducing overall complexity while maintaining effective spurious emission suppression when needed.
Solution Approach 2:
The shared duplexer architecture provides universal functionality for handling multiple uplink bands and downlink bands through a single component. By combining the shared duplexer with band-specific filters, the system achieves multi-band operation without proportionally increasing overall component count.
3Manufacturing precision
If frequency-specific filters are used for each uplink band, then spurious emissions are reduced, but the number of components and device complexity increase
Solution Approach 1:
The patent uses switches to dynamically activate only the frequency filter corresponding to the currently operating uplink band. This dynamic selection reduces the effective number of active components at any given time, maintaining high spurious emissions control precision without requiring all filters to be simultaneously active.
Solution Approach 2:
The patent pre-configures the filter network with all necessary frequency-specific filters, but uses switches to enable only the required filter before operation begins. This preliminary preparation allows the system to quickly switch between bands while maintaining precise spurious emissions control for each band.
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
This configuration allows for efficient coexistence of multiple uplink bands with adjacent downlink bands by reducing spurious emissions, enhancing the operational performance and compatibility of RF systems in multi-band environments.
Implementation Method 1
The noise filter can be configured to implement a notch filter... the noise filter circuit is configured to attenuate radio frequency noise from the amplified radio frequency transmit signal in a passband of the notch filter
Implementation Method 2
the noise filter includes one or more acoustic resonators
Data Source
AI summary
A shared-duplexer front end architecture is configured for operation in either of the 5G new radio n1 band or n65 band, while maintaining low spurious emissions in the adjacent n34 band. A front end module can have a first RF signal processing circuit for receiving RF signals from an antenna, and a second RF signal processing circuit for amplifying and transmitting RF signals via the antenna. The first RF signal processing circuit can be connected to the second RF signal processing circuit via a bypass filter circuit configured to short RF noise (particularly signal components within the n34 band) to the first RF signal processing circuit. The bypass filter circuit can be selectively enabled during transmission by the second RF signal processing circuit to effectively eliminate noise components of the RF signal and reduce spurious emissions in the n34 band.