Embedded Impedance RF Filters for Simpler Wireless Front Ends
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Solution Overview
Problem
Conventional wireless devices have complex and costly front-end RF filters due to the need for separate impedance matching circuits, which increase size and degrade performance, and the placement of TX and RX filters within a duplexer can lead to isolation issues and routing challenges.
Innovation Solution
Implementing Z-matched RF filters with embedded impedance transformation, allowing these filters to directly match with active circuits and eliminating the need for external impedance matching circuits, thereby reducing device size and cost while improving performance and simplifying routing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate impedance matching circuits are used with conventional RF filters, then impedance matching is achieved, but device size and complexity increase
Solution Approach 1:
The patent merges the impedance matching function into the RF filter structure itself. The filter is designed with specific input and output impedance characteristics that directly match the active circuits, eliminating the need for separate impedance matching circuits. This integration reduces the number of discrete components and simplifies the overall circuit architecture while maintaining proper impedance matching for optimal signal transfer.
2Reliability
If separate impedance matching circuits are used, then impedance matching is achieved, but device size increases
Solution Approach 1:
The impedance matching functionality is combined with the RF filter structure, eliminating the need for separate impedance matching circuits. The filter is designed with specific input and output impedance characteristics that directly match the active circuits, reducing the overall device area by removing redundant components and interconnections.
3Ease of operation
If TX and RX filters are placed within a duplexer, then signal routing is achieved, but isolation issues and routing challenges occur
Solution Approach 1:
The patent extracts the TX and RX filters from the traditional duplexer structure and places them in direct proximity to their respective active circuits. The TX filter is positioned near the power amplifier output, and the RX filter is positioned near the LNA input. This reconfiguration eliminates the need for complex signal routing through the duplexer and improves isolation between transmit and receive paths by physically separating the filter placements.
Data Source
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AI summary
Front-end radio frequency (RF) filters with embedded impedance transformation are disclosed. In an exemplary design, an apparatus includes an active circuit and an RF filter. The active circuit receives an input signal and provides an output signal. The RF filter is operatively coupled to an antenna and the active circuit and performs filtering for the input signal or output signal. The RF filter is impedance matched to the active circuit and includes a non-LC filter. In an exemplary design, the active circuit includes a low noise amplifier (LNA), and the RF filter includes a receive (RX) filter having an output impedance that is matched to an input impedance of the LNA. In another exemplary design, the active circuit includes a power amplifier, and the RF filter includes a transmit (TX) filter having an input impedance that is matched to an output impedance of the power amplifier.