RF Amplifier Matching Circuit With Shared LC Noise Filtering
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Solution Overview
Problem
Radio frequency amplifier circuits face challenges in suppressing noise, particularly third-order intermodulation distortion noise, which affects the linearity of power output due to the difficulty in filtering noise at frequencies close to the fundamental tone.
Innovation Solution
The proposed solution involves a radio frequency amplifier circuit that includes an amplifier, a first matching circuit, and a first inductance-capacitance resonance circuit. The matching circuit provides impedance matching for two fundamental tones, while the inductance-capacitance resonance circuit creates a filtering path that filters signal components outside the frequency band formed by these tones, effectively suppressing noise and improving linearity by sharing an inductor with the matching circuit to reduce circuit size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a filter circuit is adopted to suppress noise in the radio frequency amplifier circuit, then noise filtering capability is improved, but it is difficult to filter noise at frequencies close to the fundamental tone such as third-order intermodulation distortion noise
Solution Approach 1:
The invention segments the filtering function into multiple independent inductance-capacitance resonance circuits, each targeting specific noise frequencies. By dividing the noise suppression task into multiple frequency-specific filters rather than using a single broad filter, the circuit can effectively address third-order intermodulation distortion noise and other frequency-specific interferences while maintaining signal integrity.
Solution Approach 2:
The invention changes the filtering parameters by using adjustable inductance and capacitance values in the resonance circuits. This allows dynamic tuning of the resonance frequencies to match the specific noise frequencies present in the system, enabling effective suppression of third-order intermodulation distortion noise and other frequency-specific interferences while preserving the fundamental tone.
2Object-affected harmful factors
If multiple separate filtering circuits are used to suppress different frequency components, then noise suppression effectiveness is improved, but circuit complexity and size increase
Solution Approach 1:
The invention merges multiple filtering functions into a single integrated inductance-capacitance resonance circuit structure. By combining multiple resonance circuits with different frequency targets into one unified circuit block, the design achieves comprehensive noise suppression across multiple frequency ranges without requiring separate physical filter modules for each frequency component.
Solution Approach 2:
The inductance-capacitance resonance circuit is designed with multi-functionality, serving both as an impedance matching network and as a noise filtering system. The same inductors and capacitors that provide resonance for frequency selection also function as impedance transformation elements, eliminating the need for separate matching circuits and reducing overall circuit complexity.
3Device complexity
If traditional filtering methods are used, then circuit simplicity is maintained, but the ability to filter third-order intermodulation distortion noise is insufficient
Solution Approach 1:
The invention applies resonance theory, analogous to mechanical vibration principles, to create inductance-capacitance resonance circuits that naturally amplify or attenuate specific frequency components. By tuning the resonance frequency of each LC circuit to match the frequency of third-order intermodulation distortion noise, the system achieves selective noise suppression through resonant enhancement of the filtering effect.
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
This configuration effectively suppresses noise related to the fundamental tones, enhances the linearity of the power output, and reduces the overall size of the radio frequency amplifier circuit.
Implementation Method 1
The first inductance-capacitance resonance circuit and the first matching circuit share an inductor included in the first matching circuit to obtain a first resonance frequency
Data Source
AI summary
A radio frequency amplifier circuit is provided. A matching circuit is configured on a radio frequency path of an input end or an output end of an amplifier. An inductance-capacitance resonance circuit and the matching circuit share an inductor included in the matching circuit to generate a corresponding resonance frequency. The matching circuit provides an input impedance or an output impedance matching two fundamental tones in a radio frequency signal at a first frequency and a second frequency. The inductance-capacitance resonance circuit provides a filtering path for filtering a signal component outside a frequency band formed by the first frequency and the second frequency in the radio frequency signal.