Parallel Resonant Switch for RF Front End Insertion Loss
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Solution Overview
Problem
Conventional multi-band front ends experience efficiency degradation due to insertion loss from mode switches and challenges in managing loading effects between signal paths, particularly when sharing a common RF input/output terminal.
Innovation Solution
A novel parallel resonant switch design that eliminates insertion loss by using a transformer and switches to switch between power amplifier outputs, controlling the loading effects by forming a parallel resonant circuit or matching network based on the transmit mode, thereby reducing signal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mode switches are used to select between multiple signal paths in a conventional multi-band front end, then band selection is enabled, but insertion loss occurs which degrades overall efficiency
Solution Approach 1:
The patent removes the mode switch from the signal path entirely, extracting the problematic component that causes insertion loss. Instead of using a switch to select bands, the invention uses separate amplifiers with a parallel resonant circuit that naturally isolates frequency bands without requiring the signal to pass through a switching mechanism, thereby eliminating insertion loss while maintaining band selection capability.
Solution Approach 2:
The parallel resonant circuit acts as an intermediary between multiple amplifiers and the common RF terminal. This mediator enables frequency-based isolation and band selection without requiring direct switching of the signal path, allowing multiple amplifiers to operate simultaneously on different bands without mutual interference or loss.
2Adaptability or versatility
If multiple power amplifiers share a common RF input/output terminal, then multiple bands can be driven, but loading effects between signal paths occur which degrade performance
Solution Approach 1:
The patent employs resonant frequency principles where the parallel resonant circuit is tuned to specific frequency bands. At its resonant frequency, the circuit presents high impedance to signals of that frequency while presenting low impedance to other frequencies, thereby naturally isolating signal paths without requiring additional switching components. This resonance-based isolation maintains reliable signal transmission across multiple bands.
3Device complexity
If a single power amplifier and matching network are used, then device complexity is reduced, but efficiency degradation occurs due to insertion loss from mode switches
Solution Approach 1:
The patent segments the amplification function into multiple independent power amplifiers, each optimized for specific frequency bands. This segmentation eliminates the need for mode switches that cause insertion loss, as each amplifier operates independently on its designated band. The parallel resonant circuit provides the necessary frequency separation, maintaining overall system efficiency while achieving multi-band capability.
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 minimizes insertion loss and controls signal path loading, improving linearity and reducing impedance mismatch, leading to enhanced efficiency in switching between multiple transmit and receive signals in wireless devices.
Implementation Method 1
a parallel resonant switch design that eliminates insertion loss by using a transformer and switches to switch between power amplifier outputs, controlling the loading effects by forming a parallel resonant circuit or matching network based on the transmit mode
Data Source
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AI summary
A front end parallel resonant switch (102) is disclosed. In an exemplary embodiment, an apparatus includes an inductor (L2) and a capacitor (CI) configured to couple a first RF transmission (112) to an antenna (110), and at least one switch (SWl, SW2, SW3) configured to connect the inductor (L2) to the capacitor (CI) to form a matching network when transmitting the first RF transmission (112) from the antenna (110), and to connect the inductor (L2) to capacitor (CI) to form a parallel resonant circuit when transmitting a second RF transmission (122) from the antenna (110). The resonant switch operates without the use of in-line mode switches to eliminate insertion loss associated with the use of in-line mode switches. The resonant switch also operates to control the loading effects of one transmit signal on the other transmit signal so as to reduce signal degeneration.