RF Modulation Signal Injection for Power Amplifier Linearity
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Solution Overview
Problem
The increasing frequency width required for 5G communications leads to serious signal distortion in power amplifiers, limiting output power and efficiency, despite the use of power back-off technology to reduce distortion.
Innovation Solution
A linearity improving system and method that uses a modulation signal injection mechanism, comprising a coupler, downconverter, and transformer to adjust the phase and power of the input RF signal, thereby enhancing the linearity of the amplifier when transmitting broadband signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the frequency width of modulation signal is increased to achieve higher transmission data quantity for 5G communications, then the transmission bandwidth is increased, but the signal distortion in power amplifier becomes more serious
Solution Approach 1:
An auxiliary modulation signal is introduced as an intermediary to interact with the main RF signal in the power amplifier. This auxiliary signal, generated by downconverting and processing a portion of the input RF signal, serves to cancel or reduce the distortion components produced by the power amplifier's nonlinear operation, thereby improving overall signal linearity while maintaining high transmission bandwidth
Solution Approach 2:
The system employs a feedback mechanism where a portion of the input RF signal is extracted, downconverted to baseband, processed through variable gain amplifiers, and then fed back to the power amplifier input. This feedback loop continuously adjusts the auxiliary modulation signal to counteract the distortion generated by the power amplifier, enabling dynamic linearity improvement across varying transmission conditions
2Object-generated harmful factors
If power back-off technology is used to reduce signal distortion in power amplifier, then the degree of signal distortion is reduced, but the efficiency of the power amplifier deteriorates
Solution Approach 1:
Instead of reducing the main RF signal power (power back-off), the invention introduces an auxiliary modulation signal as a mediator that actively compensates for distortion. This allows the power amplifier to operate at higher efficiency levels while the auxiliary signal cancels out the distortion components, eliminating the need for efficiency-reducing power back-off techniques
Solution Approach 2:
The invention converts the harmful distortion generated by the power amplifier into a beneficial effect by using the same nonlinear distortion mechanism to generate an auxiliary signal that, when properly phased and amplitude-adjusted, cancels the original distortion. The distortion is not eliminated at the source but is transformed into a corrective element that improves overall linearity
3Reliability
If a modulation signal injection mechanism is used to improve the linearity of amplifier, then the linearity is improved and output power and efficiency are increased, but the device complexity increases
Solution Approach 1:
The system achieves multi-functionality by using the same signal processing chain for multiple purposes: the downconverter and variable gain amplifiers not only generate the auxiliary modulation signal for linearity improvement but also provide signal routing and gain control functions. This universal approach reduces the need for separate dedicated components, thereby limiting the increase in device complexity
Solution Approach 2:
The invention merges the auxiliary signal generation path with the main RF signal path by using the same input RF signal as the source for both the main amplification chain and the auxiliary modulation signal generation. This consolidation of signal sources and processing functions reduces component count and system complexity compared to using entirely separate signal paths
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 improves the linearity of power amplifiers, allowing for higher output power and efficiency while reducing signal distortion and neighboring channel leakage power, particularly in 5G communication systems.
Implementation Method 1
a coupler (110), configured to couple a part of an input RF signal
Implementation Method 2
The downconverter converts the input RF signal to a fundamental frequency and outputs a modulation signal
Implementation Method 3
The transformer is used to adjust a phase and a power of the modulation signal
Data Source
AI summary
A linearity improving system and a linearity improving method are provided. The linearity improving system includes a coupler, a downconverter and a transformer. The coupler is configured to couple a part of an input RF signal. The downconverter coupled to the coupler converts the input RF signal to a fundamental frequency and outputs a modulation signal. The transformer coupled to the downconverter adjusts a phase and a power of the modulation signal. After the input RF signal and the modulation signal being adjusted are inputted to an amplifier, the amplifier outputs an output RF signal.