RF Front End Shared Path with Common Filter
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Solution Overview
Problem
RF communication systems face challenges in achieving high rejection and low insertion loss in TDD modes, especially when bands are closely spaced, leading to coexistence issues between cellular and WiFi signals, and stringent regulatory requirements for 5G NR bands.
Innovation Solution
The implementation of a radio frequency front end system with separate transmit and receive filters, multiplexers, and switches that allow for simultaneous operation of multiple bands, using a single-pole N-throw or double-pole quadruple-throw switches to manage signal paths efficiently, and employing supplemental filters to address specific interference issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common filter is shared between transmit and receive paths in TDD mode, then device complexity is reduced, but rejection of blockers and insertion loss performance deteriorate when bands are closely spaced
Solution Approach 1:
The filter system is segmented into separate transmit filters and receive filters that can be independently selected and configured. This segmentation allows each filter to be optimized for its specific function (transmit or receive) while maintaining the ability to handle closely spaced bands through independent filter selection, thereby improving blocker rejection performance without requiring a completely unified filter system.
2Reliability
If separate transmit and receive filters are used in TDD mode, then blocker rejection and insertion loss performance improve, but device complexity and component quantity increase
Solution Approach 1:
The filter system is designed with universal filter components that can function in both transmit and receive paths. Multiple filters are configured such that they can be selectively applied to different bands and paths, allowing a single set of filter components to serve multiple functions across different operating conditions, thereby reducing overall system complexity while maintaining high performance.
Solution Approach 2:
The filter configuration is made dynamic through switching mechanisms that allow real-time selection of appropriate filters based on the current operating band and mode (transmit or receive). This dynamic reconfiguration capability enables the system to adapt to different operational requirements without requiring permanent dedicated filters for each scenario, optimizing performance while managing complexity.
3Adaptability or versatility
If multiple bands are operated simultaneously, then system versatility and communication capability improve, but signal interference and coexistence issues worsen
Solution Approach 1:
Different filter characteristics are applied to different frequency bands based on their specific requirements. Each band can have locally optimized filter settings that address its particular interference challenges, allowing the system to handle multiple bands simultaneously with minimal mutual interference by tailoring the filtering properties to each band's specific needs.
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 enhances the rejection of blockers, reduces insertion loss, and meets regulatory requirements for 5G NR bands, improving the coexistence of cellular and WiFi signals while maintaining high efficiency and compact design.
Implementation Method 1
at least one power amplifier configured to amplify a transmit radio frequency signal
Implementation Method 2
at least one low noise amplifier configured to receive a receive radio frequency signal
Implementation Method 3
one or more filters configured to filter out frequencies from the RF signals that are not within a given communication band
Implementation Method 4
at least one switch configured to selectively couple the output node to the at least one power amplifier during a transmit period and to the at least one low noise amplifier during a receive period
Data Source
AI summary
Radio frequency front end modules are provided. In one aspect, a front end system includes at least one power amplifier configured to amplify a transmit radio frequency signal, at least one low noise amplifier configured to receive a receive radio frequency signal, an output node coupled to an antenna. The front end system further includes at least one switch configured to selectively couple the output node to the at least one power amplifier during a transmit period and to the at least one low noise amplifier during a receive period, at least one transmit filter coupled between the power amplifier and the at least one switch, and at least one receive filter coupled between the low noise amplifier and the at least one switch.