Multiband Power Amplifier Filters for Low-Loss Signal Routing
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Solution Overview
Problem
Existing power amplifier circuits for multiband mobile communication terminals face challenges in maintaining power gain due to the need for small capacitance in LC parallel resonance circuits, which increases signal loss for one frequency band while attenuating the other.
Innovation Solution
A power amplifier circuit design that includes separate filters for each frequency band, using an inductor as the path for the lower frequency signal and a capacitor as the path for the higher frequency signal, reducing signal loss by eliminating switches in the transmit path and utilizing matching circuits to attenuate harmonics and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a capacitor of small capacitance is used in the first LC parallel resonance circuit to attenuate the second frequency signal, then the attenuation of the second frequency is improved, but the loss of the first frequency signal increases
Solution Approach 1:
The patent divides the frequency filtering function into two separate circuits: one dedicated to attenuating the second frequency and another for the first frequency. This segmentation allows each circuit to be optimized for its specific frequency without compromising the other, resolving the contradiction between attenuating one frequency and maintaining signal strength at another frequency.
Solution Approach 2:
The patent introduces a switching mechanism as an intermediary element that controls the connection of capacitors to the LC parallel resonance circuits. This switching intermediary allows the system to dynamically adjust which capacitor is connected based on the operating frequency, thereby achieving effective attenuation of the unwanted frequency while minimizing signal loss at the desired frequency.
2Adaptability or versatility
If switches are included in the LC parallel resonance circuits to enable frequency switching, then the adaptability to different frequency bands is improved, but the device complexity and signal loss increase
Solution Approach 1:
The patent implements dynamic switching of capacitor connections based on the operating frequency band. The switching mechanism dynamically reconfigures the circuit by connecting different capacitors to the LC parallel resonance circuits, enabling the system to adapt to different frequency bands while maintaining relatively simple circuit architecture.
Solution Approach 2:
The LC parallel resonance circuit is designed to serve multiple frequency bands by switching between different capacitor configurations. This multi-functionality allows a single circuit structure to handle both first and second frequency bands, reducing overall device complexity compared to having separate dedicated circuits for each frequency band.
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 design effectively reduces signal loss for both frequency bands, allowing the power amplifier circuit to maintain power gain while minimizing area and component count, thus enhancing efficiency and reducing leakage of harmonics.
Implementation Method 1
The first filter includes a first inductor and attenuates the second signal amplified in the power amplifier. The first inductor serves as a path for the first signal amplified in the power amplifier.
Implementation Method 2
The second filter includes a first capacitor and attenuates the first signal amplified in the power amplifier. The first capacitor serves as a path for the second signal amplified in the power amplifier.
Implementation Method 3
The power amplifier is able to amplify both of a first signal and a second signal
Data Source
AI summary
A power amplifier circuit includes a power amplifier, first and second filters, and first and second output paths. The power amplifier is able to amplify both of a first signal and a second signal. The frequency of the second signal is higher than that of the first signal. The first filter includes a first inductor and attenuates the second signal amplified in the power amplifier. The first inductor serves as a path for the first signal amplified in the power amplifier. The second filter includes a first capacitor and attenuates the first signal amplified in the power amplifier. The first capacitor serves as a path for the second signal amplified in the power amplifier. The first signal outputted from the first filter is supplied to the first output path. The second signal outputted from the second filter is supplied to the second output path.