RF Amplifier Feedforward Compensation for Blocker Filtering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wireless communication systems using surface acoustic wave (SAW) filters as external devices increase the cost of wireless transceivers, especially in multi-band structures, due to the need for separate filters for each frequency band, and struggle with effective blocker signal removal.
Innovation Solution
A radio frequency (RF) amplifier with a feedforward path incorporating a gain/phase compensator, high-pass filter, and mixer, which adjusts gain and phase based on the frequency band of blockers, allowing for improved blocker filtering performance without bulky off-chip devices like SAW filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SAW filters are used as external devices for blocker signal removal, then blocker filtering performance is improved, but device cost and complexity increase
Solution Approach 1:
The patent combines the blocker filtering function with the RF amplifier by integrating a feedforward path into the amplifier structure. The feedforward path includes a blocker filter that processes blocker signals, and this path is merged with the main signal path through adders and phase shifters, eliminating the need for separate external SAW filters while maintaining filtering performance
Solution Approach 2:
The RF amplifier is designed to perform multiple functions simultaneously: signal amplification through the main path and blocker signal filtering through the integrated feedforward path. The amplifier structure itself serves as the filtering platform, making the device universal for both amplification and rejection functions without requiring additional external components
2Reliability
If separate SAW filters are used for each frequency band in multi-band transceivers, then blocker filtering performance for each band is improved, but device cost increases significantly
Solution Approach 1:
The patent designs the RF amplifier with a multi-functional feedforward path that can operate across multiple frequency bands. The blocker filter and associated components are configured to handle different frequency bands through the same structural framework, allowing a single amplifier device to serve multiple bands without requiring separate filters for each band
Solution Approach 2:
The patent incorporates variable gain amplifiers and adjustable phase shifters in the feedforward path that can be dynamically configured for different frequency bands. This dynamic adaptability allows the same hardware structure to be tuned for multiple bands, eliminating the need for static, band-specific external filters
3Device complexity
If conventional RF amplifiers without feedforward paths are used, then device simplicity is maintained, but blocker signal removal capability is insufficient
Solution Approach 1:
The patent extracts the blocker signal processing function from the main signal path by creating a separate feedforward path dedicated to blocker filtering. This extracted path includes a blocker filter, variable gain amplifier, and phase shifter that specifically target blocker signals without interfering with the main amplification function
Solution Approach 2:
The feedforward path performs preliminary processing on blocker signals before they can interfere with the desired signal. The blocker filter preemptively attenuates blocker signals, and the variable gain amplifier and phase shifter pre-adjust the blocker path signal to enable effective cancellation when combined with the main path through the adder
Data Source
AI summary
Disclosed is a radio frequency (RF) amplifier having channel selectivity. The RF amplifier includes a main path including an amplifier, and a feedforward path including a gain/phase compensator, a high-pass filter, and a mixer.