High Frequency Module Variable Impedance Circuit Distortion Control
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Solution Overview
Problem
Existing high frequency modules fail to effectively reduce secondary and tertiary distortion components, leading to adjacent channel interference due to non-linear amplifier characteristics, especially when frequency bandwidth changes.
Innovation Solution
A high frequency module with an amplifier circuit and a variable impedance circuit, where the output impedance changes based on control signals, utilizing a voltage follower circuit as a buffer to isolate high frequency signals and prevent interference, and an output matching network to reflect secondary distortion components, thereby reducing unwanted signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a low-pass filter is formed using a passive device at the bias portion of an amplification transistor, then the impedance can be adjusted, but high frequency components of multiple frequencies generated due to frequency bandwidth changes cannot be effectively reduced
Solution Approach 1:
The patent applies a variable impedance circuit that dynamically adjusts its impedance characteristics based on the frequency bandwidth of the input signal. Unlike the static passive low-pass filter in prior art, this circuit can adapt its impedance profile to match different frequency conditions, enabling effective reduction of high frequency distortion components across varying bandwidth scenarios while maintaining proper impedance matching.
Solution Approach 2:
The invention changes the impedance parameter dynamically according to the frequency bandwidth of the input signal. By controlling the impedance of the variable impedance circuit based on detected frequency characteristics, the system can optimize both impedance matching and high frequency component reduction for different operating conditions, resolving the contradiction between fixed impedance adjustment and variable frequency requirements.
2Adaptability or versatility
If the frequency bandwidth is changed, then the communication signal can be transmitted, but the linearity deteriorates due to non-linear amplifier characteristics
Solution Approach 1:
The variable impedance circuit dynamically adjusts its characteristics in response to different frequency bandwidth inputs, enabling the amplifier to maintain optimal operating conditions across various bandwidth scenarios. This dynamic adaptation prevents the degradation of linearity that would otherwise occur when operating at different frequency ranges.
Solution Approach 2:
The system incorporates feedback mechanisms that detect the frequency bandwidth of the input signal and use this information to control the variable impedance circuit. This feedback loop ensures that the impedance is optimally adjusted for each frequency condition, thereby maintaining signal linearity and preventing distortion across different operating frequencies.
3Device complexity
If a fixed impedance circuit is used, then the circuit design is simplified, but the output impedance cannot be adjusted according to frequency bandwidth changes
Solution Approach 1:
The patent implements a variable impedance circuit that provides dynamic adaptability to different frequency bandwidths. While this increases circuit complexity compared to a fixed impedance design, it enables the system to effectively handle multiple frequency conditions and maintain optimal performance across varying operational requirements.
Solution Approach 2:
The variable impedance circuit serves multiple functions: it provides impedance matching for different frequency bandwidths, reduces high frequency distortion components, and maintains signal linearity across various operating conditions. This multi-functionality justifies the increased complexity by delivering comprehensive performance optimization that a simple fixed impedance circuit cannot achieve.
Data Source
AI summary
When the frequency bandwidth of a high frequency signal to be amplified is changed, the linearity of a high frequency module deteriorates. A high frequency module has an amplifier circuit including an amplification transistor and a variable impedance circuit, and an output matching network. Based on an amplifying operation, the amplified high frequency signal will contain unwanted signals of secondary distortion components. In a frequency band that generates such unwanted signals of secondary distortion components, the output impedance of the amplifier circuit is changed so that the impedance will not match between the amplifier circuit and the output matching network. The output impedance of the amplifier circuit is changed by controlling the variable impedance circuit.