Reconfigurable Output Matching Network for Multi-Band RF Amplifiers
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Solution Overview
Problem
Current multi-band RF power amplifiers face challenges in reducing cost and size while maintaining performance, as they often require multiple power amplifiers or compromise on efficiency due to the use of switches at low impedance points for frequency band selection.
Innovation Solution
A reconfigurable output matching network with a plurality of impedance matching circuits, where only one circuit is active at a time, each optimized for a specific frequency band, and inactive circuits exhibit a high impedance, minimizing power loss and enhancing efficiency by providing harmonic impedance termination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple separate power amplifiers are used for multi-band operation, then each frequency band achieves optimized performance, but cost and device size increase
Solution Approach 1:
The patent combines multiple frequency band handling capabilities into a single power amplifier by integrating multiple matching networks within one device. Each matching network is designed for specific frequency bands (e.g., LTE, GSM, WCDMA), allowing the single amplifier to serve multiple bands simultaneously through impedance transformation, eliminating the need for separate amplifiers for each band.
Solution Approach 2:
The single power amplifier is designed with universal capability to handle multiple frequency bands through the integrated matching networks. The amplifier can be configured to operate across different bands (700MHz, 800MHz, 900MHz, 1800MHz, 2100MHz, 2600MHz) by selecting appropriate matching networks, making one device perform functions that traditionally required multiple specialized devices.
2Device complexity
If switches are inserted for frequency band selection, then a single power amplifier can be used, but on-state switch loss degrades overall efficiency
Solution Approach 1:
The patent extracts the frequency selection function from switch-based mechanisms and implements it through passive matching networks with high impedance isolation. Instead of using active switches to select between frequency bands, the design uses multiple matching networks where inactive networks present high impedance to prevent signal leakage, eliminating the need for switches and their associated on-state losses.
Solution Approach 2:
The matching networks serve as intermediaries between the single power amplifier and the antenna, providing frequency-specific impedance transformation. Each matching network is tuned to specific frequency bands and presents high impedance to other bands, acting as a passive selector that directs signals without requiring active switching components.
3Ease of operation
If a wideband matching network is used, then impedance matching is achieved, but the power amplifier cannot achieve different output power requirements for different frequency bands
Solution Approach 1:
The patent segments the matching network function into multiple frequency-specific matching networks instead of using a single wideband network. Each matching network is optimized for specific frequency bands and impedance requirements, allowing the system to provide both impedance matching and frequency-specific output power control by activating the appropriate matching network for each band.
Data Source
AI summary
An output matching network comprising a plurality of impedance matching circuits. The inputs of each of the plurality of impedance matching circuits are connected to a first input of the output matching network. The outputs of each of the plurality of impedance matching circuits are connected to a plurality of first outputs of the output matching network. One of the plurality of impedance matching circuits is active at a given time. The active impedance matching circuit of the plurality of impedance matching circuits exhibits a first input impendence at a first frequency band. Each inactive impedance matching circuit of the plurality of impedance matching circuits exhibits a second input impedance at the first frequency band. The second input impendence is at least 10 times greater than the first input impendence.