Multiplexed RF Filter Bank Switching for Lower Insertion Loss
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Solution Overview
Problem
Conventional tunable RF frontend filters face challenges in meeting filtering requirements such as insertion loss, rejection demands, and Q factors, especially as the demand for narrower bandwidths and wider frequency coverage increases, leading to increased complexity and costs in switching solutions.
Innovation Solution
The proposed filter architecture utilizes multiplexing of inputs and outputs of a filter bank, combined with careful allocation of switch throws, to simplify and improve the performance of filter solutions. This is achieved by configuring input and output switches to select specific filters within the filter bank, ensuring that each filter is multiplexed with different filters at both the input and output sides, and that switch throws are optimized to reduce complexity and insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of individual filters in a filter bank increases to meet narrower bandwidths and wider frequency coverage, then frequency selectivity and coverage are improved, but the complexity of input and output switching increases
Solution Approach 1:
The patent merges multiple filter selections into a single-pole multiple-throw switch configuration. Instead of requiring separate switching paths for each filter, the invention combines the selection function into one switch that can connect the RF input to any one of multiple filters, and similarly combines the output selection into another single switch. This merging reduces the overall switching complexity while maintaining the ability to select from a large number of filters for wide frequency coverage.
Solution Approach 2:
The input and output switches are designed as universal multi-function components. The single-pole multiple-throw input switch can route signals to any filter in the filter bank, and the corresponding output switch can route outputs from any filter to the RF output. This universal switching architecture eliminates the need for dedicated switching paths for each filter combination, reducing complexity while maintaining adaptability across the entire frequency range.
2Measurement precision
If more filters are added to the filter bank, then frequency selectivity is improved, but the area and cost of switching solutions increase
Solution Approach 1:
The patent merges the switching functions into compact single-pole multiple-throw configurations rather than using distributed switching networks. By combining multiple filter selection functions into unified input and output switches, the physical area required for switching is dramatically reduced while still supporting a large number of filters for high frequency selectivity.
Solution Approach 2:
The invention transitions from a distributed two-dimensional switching matrix to a centralized single-pole multiple-throw switch architecture. This dimensional change consolidates the switching function into a more compact form factor, reducing the area occupied by switching components while maintaining the ability to selectively connect any filter to the RF input and output.
3Adaptability or versatility
If complex switching solutions are used to select filters, then filter selection capability is improved, but insertion loss increases
Solution Approach 1:
The patent merges the filter selection function into direct single-pole multiple-throw switch connections rather than using complex multi-stage switching networks. This direct connection approach minimizes the number of switching stages and associated insertion losses while maintaining full filter selection capability across the frequency range.
Solution Approach 2:
The invention optimizes the local quality of each switching path by using direct single-pole multiple-throw connections that provide low-loss signal paths. Each switch is designed to provide optimal isolation and minimal insertion loss for its specific throw connections, ensuring that the selected filter path maintains high signal integrity while still enabling broad filter selection capability.
4Ease of operation
If the number of switches and switch throws increases, then filter bank control is improved, but routing complexity increases
Solution Approach 1:
The patent merges the control functions into coordinated single-pole multiple-throw switch pairs. The input switch and output switch work together as a unified control system, where selecting a specific filter involves coordinating the throws of both switches. This merging reduces routing complexity by eliminating the need for complex multi-switch coordination while maintaining ease of filter bank control through the simplified switch pair architecture.
Data Source
AI summary
The present disclosure relates to a filter architecture, which includes a filter bank with multiple filters, an input switch coupled to an input side of the filter bank, and an output switch coupled to an output side of the filter bank. Each filter is multiplexed with one or more different filters at the input side and the output side of the filter bank. At a given time, the input switch is controlled to connect a first group of the filters to a radio frequency (RF) input terminal, and the output switch is controlled to connect a second group of the filters to an RF output terminal. Herein, the first group and the second group have one filter in common, such that the input switch and the output switch are configured to select one of the filters to operate at the given time.