Power Amplifier Interference Cancellation for Antenna Coupling
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Solution Overview
Problem
Existing radio frequency systems face challenges in managing interference between antennas in antenna arrays due to limited isolation, leading to degradation in linearity and efficiency of power amplifiers, particularly in high-frequency and massive MIMO systems.
Innovation Solution
Implementing an interference cancellation loop in power amplifier systems that includes a radio frequency coupler and a phase shifter to generate a cancellation signal, which suppresses interference at the output of the power amplifier, thereby reducing the need for isolators and improving linearity without significant loss in efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If antennas in an antenna array operate concurrently with independent streams, then system capacity and spectral efficiency are improved, but interference between antennas degrades power amplifier linearity
Solution Approach 1:
The patent captures the interfering signal using a radio frequency coupler and converts this harmful interference into a useful cancellation signal. The interference sensing circuit detects the interfering power, which is then processed through an amplifier and phase shifter to generate a cancellation signal that is injected back into the transmit signal path, thereby converting the harmful interference into a beneficial cancellation effect that improves power amplifier linearity
Solution Approach 2:
The patent introduces an interference cancellation loop as an intermediary system between the interfering signal source and the power amplifier output. This loop includes a radio frequency coupler for sensing, an amplifier for signal processing, and a phase shifter for phase adjustment, which together mediate the interference by generating and injecting a cancellation signal that neutralizes the harmful effects of antenna coupling interference
2Manufacturing precision
If isolators are added to reduce antenna coupling interference, then power amplifier linearity is improved, but system efficiency decreases due to additional power loss
Solution Approach 1:
Instead of using isolators that dissipate interference energy as heat, the patent converts the harmful interfering signal into a useful cancellation signal. The interference sensing circuit captures the interfering power, which is then amplified and phase-shifted to create a cancellation signal that actively neutralizes the interference, thereby improving linearity without the energy losses associated with passive isolators
Solution Approach 2:
The patent implements a feedback-based interference cancellation mechanism where the interfering signal is sensed, processed, and fed back as a cancellation signal to the transmit path. The interference sensing circuit continuously monitors the interfering power, and the cancellation loop adjusts the cancellation signal in real-time to maintain optimal linearity performance, creating a dynamic feedback system that improves efficiency compared to static isolators
3Manufacturing precision
If interference cancellation circuitry is implemented, then power amplifier linearity is improved, but device complexity increases
Solution Approach 1:
The interference cancellation loop components serve multiple functions: the radio frequency coupler both senses interfering power and couples the cancellation signal back into the transmit path; the amplifier both amplifies the sensed interference and provides gain control for the cancellation signal; the phase shifter both measures phase information and adjusts the cancellation signal phase. This multi-functionality reduces the need for separate dedicated components, thereby managing complexity while achieving linearity improvement
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 interference cancellation loop effectively suppresses interference, enhancing power amplifier linearity and reducing out-of-band emissions, allowing for wide beam scanning angles and improved spectral efficiency in antenna arrays.
Implementation Method 1
The radio frequency coupler is configured to generate an interfering power signal
Implementation Method 2
The interference cancellation loop includes an amplifier and a phase shifter, the interference cancellation loop configured to receive the interfering power signal and to provide a cancellation signal
Implementation Method 3
the interference cancellation loop configured to generate the cancellation signal by at least amplifying and phase shifting the interfering power signal using the amplifier and the phase shifter
Implementation Method 4
provide a cancellation signal to the transmit signal path to thereby suppress interference at the output of the power amplifier
Data Source
Figure 1~2
Figure 3
Figure 4A
AI summary
Aspects of this disclosure relate to a cancelling interference at an output of a power amplifier. An interference sensing circuit in a signal path between the power amplifier and an antenna can generate an interfering power signal. An interference cancellation loop can receive the interfering power signal and provide a cancellation signal to a transmit signal path that includes the power amplifier to thereby suppress interference at the output of the power amplifier. In certain embodiments, the interference cancellation loop includes an amplifier and a phase shifter. Related systems and methods are disclosed.