Multi-Frequency LNA Matching Network for Out-of-Band Rejection
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Solution Overview
Problem
Existing multi-frequency low noise amplifiers face challenges in achieving optimal performance across multiple frequency bands due to the complexity and cost associated with using wide-band or narrow-band amplifiers, which result in suboptimal gain, noise figures, and increased component count.
Innovation Solution
A multi-frequency low noise amplifier is designed with a single circuit structure that includes input and output matching networks with out-of-band rejection and frequency band selection circuits, allowing for efficient rejection of unwanted frequency bands and optimization of each frequency band for optimal noise figures, gain, and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a wide-band low noise amplifier is used to support multiple frequency bands, then the device complexity is reduced, but the noise figure and gain performance deteriorate across different frequency bands
Solution Approach 1:
The patent divides the wide frequency band into multiple narrow frequency bands, with each narrow-band LNA optimized for a specific frequency range. This segmentation allows each amplifier to achieve optimal noise figure and gain for its designated band, while the overall system supports multiple bands through selective switching.
Solution Approach 2:
The patent employs dynamic frequency band selection circuits and switching mechanisms that adaptively connect different narrow-band LNAs based on the input signal frequency. This dynamic reconfiguration enables the system to maintain optimal performance across varying frequency bands while keeping the overall device complexity manageable.
2Reliability
If multiple narrow-band low noise amplifiers are used for each frequency band, then the noise figure and gain performance is improved, but the device complexity and component count increase
Solution Approach 1:
The patent designs each narrow-band LNA to serve multiple purposes: providing optimal amplification for its specific frequency band, contributing to overall multi-band support, and enabling frequency selection through the band selection circuits. This multi-functionality reduces the need for separate dedicated circuits for each function.
Solution Approach 2:
The patent introduces frequency band selection circuits as intermediary components between the multiple narrow-band LNAs and the output stage. These selection circuits act as mediators that dynamically connect the appropriate LNA based on the input frequency, simplifying the overall system architecture compared to having fully independent amplifier chains for each band.
3Object-affected harmful factors
If frequency band selection circuits are added to the amplifier, then the out-of-band rejection capability is improved, but the device complexity increases
Solution Approach 1:
The patent combines the frequency band selection functionality with the amplifier input matching networks and output loading circuits. By merging these functions into unified circuits that serve both amplification and frequency selection purposes, the overall device complexity is reduced compared to having separate independent circuits for each function.
Data Source
AI summary
A multi-frequency low noise amplifier includes an input matching network, an amplifying circuit and an output matching network. The input matching network includes a first out-of-band rejection circuit and a first frequency band selection circuit. The output matching network includes a second out-of-band rejection circuit and a second frequency band selection circuit. The first out-of-band rejection circuit can reject signal of any frequency band in the radio frequency signals so that signals of the remaining frequency bands can pass through. The first frequency band selection circuit can screen out the signals of reference frequency spots from the remaining frequency bands. The second frequency band selection circuit can screen out the signals of partial frequency spots from the amplified signals of reference frequency spots. The second out-of-band rejection circuit can reject the signal of any frequency spot in the signals of partial frequency spots.