Power Amplifier Reverse Coupling for rIMD Cancellation
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Solution Overview
Problem
Mobile communication devices face challenges in suppressing reverse intermodulation products (rIMDs) due to antenna coupling, which can lead to non-compliance with regulatory spurious emissions (SEM) requirements, especially in non-contiguous RF bands like LTE and 5G-NR bands 41, where additional filters are difficult to implement effectively.
Innovation Solution
A power amplifier apparatus with a reverse coupling circuit that generates an interference cancellation signal to suppress rIMDs by amplifying and phase-shifting the signal to match the reverse interference, ensuring compliance with SEM requirements through concurrent transmission and reception in multiple RF spectrums.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If additional filters are employed to suppress reverse interference signal and rIMDs, then spurious emissions compliance is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent converts the harmful reverse interference signal into a useful cancellation signal by capturing it through the reverse coupling circuit, processing it to create an inverted version, and injecting it back to cancel the original interference. This transforms the harmful rIMDs into a solution for suppressing spurious emissions without adding complex filters.
Solution Approach 2:
The reverse coupling circuit acts as an intermediary element that captures the reverse interference signal from the antenna port, processes it through phase shifters and attenuators, and generates the cancellation signal. This intermediary approach provides a cleaner solution compared to directly filtering the output path.
2Object-affected harmful factors
If power amplifier output power is reduced to suppress rIMDs, then spurious emissions compliance is improved, but transmission power and data rate performance deteriorate
Solution Approach 1:
Instead of reducing power to suppress rIMDs, the patent uses the reverse interference signal itself as the source for generating the cancellation signal. The harmful high-power reverse signal is processed and inverted to create an equal and opposite cancellation signal, maintaining full transmission power while achieving rIMD suppression.
Solution Approach 2:
The cancellation signal is generated and injected into the amplifier input in advance to preemptively counteract the rIMDs before they are generated and transmitted. This preliminary anti-action occurs at the input stage rather than attempting to suppress after the harmful signals are created.
3Object-affected harmful factors
If conventional filtering approaches are used for non-contiguous RF bands, then signal isolation is improved, but implementation feasibility and ease of manufacture deteriorate
Solution Approach 1:
The reverse coupling circuit serves multiple functions: it captures reverse interference signals, generates cancellation signals, and adapts to different RF bands through programmable phase shifters and attenuators. This universal approach works for both contiguous and non-contiguous bands without requiring band-specific filter designs.
Solution Approach 2:
The system uses programmable phase shifters and attenuators that can be dynamically adjusted through digital control to adapt to different RF bands and interference conditions. This dynamic configuration is easier to manufacture and implement than fixed broadband filters for non-contiguous bands.
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 suppresses rIMDs to a defined threshold, enabling concurrent LTE and 5G-NR transmissions while meeting stringent SEM requirements without the need for large additional power reduction, thus ensuring reliable and compliant operation in mobile communication devices.
Implementation Method 1
The amplifier circuit is configured to amplify the interference cancellation signal and the RF signal to create an intermodulation product(s) to suppress the rIMD(s)
Implementation Method 2
A reverse coupling circuit is provided in the power amplifier apparatus to generate an interference cancellation signal based on the reverse interference signal (e.g., with opposing phase and proportional amplitude relative to the reverse interference signal)
Data Source
AI summary
A power amplifier apparatus supporting reverse intermodulation product (rIMD) cancellation is provided. The power amplifier apparatus includes an amplifier circuit configured to amplify and output a radio frequency (RF) signal for transmission via an antenna port. The antenna port may receive a reverse interference signal, which may interfere with the RF signal to create a rIMD(s) that can fall within an RF receive band(s). A reverse coupling circuit is provided in the power amplifier apparatus to generate an interference cancellation signal based on the reverse interference signal. The amplifier circuit is configured to amplify the interference cancellation signal and the RF signal to create an intermodulation product(s) to suppress the rIMD(s) to a determined threshold. By suppressing the rIMD(s) in the power amplifier apparatus, it is possible to support concurrent transmissions and receptions in a number of RF spectrums while in compliance with stringent regulatory spurious emissions (SEM) requirements.