RF Power Amplifier Matching for Harmonic Suppression Across Adjacent Bands
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Solution Overview
Problem
Existing high frequency amplification circuits face challenges in attenuating harmonics of high frequency signals, leading to increased transmission loss and interference with adjacent frequency bands, particularly when signals from bands at the high frequency end of a frequency band group are transmitted.
Innovation Solution
The proposed solution involves a high frequency amplification circuit with a first transmission amplification circuit for the first frequency band group, a second transmission amplification circuit for an adjacent frequency band group, and output matching circuits that include low-pass filters and impedance-variable circuits to optimize impedance matching and attenuate harmonics, allowing for low-loss transmission of signals across multiple frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the attenuation circuit is optimized to sufficiently attenuate the harmonic of the first band, then the harmonic interference is suppressed, but the transmission loss of the second band adjacent to the high frequency side is worsened
Solution Approach 1:
The patent divides the frequency band handling into two separate amplification circuits: a first amplification circuit for the first frequency band group and a second amplification circuit for the second frequency band group. This segmentation allows each circuit to be optimized independently - the first circuit can focus on harmonic attenuation while the second circuit prioritizes low transmission loss for adjacent bands.
Solution Approach 2:
The patent employs a switching circuit that dynamically selects which amplification circuit to use based on the input signal's frequency band. This dynamic allocation ensures that signals from the first band group pass through the circuit optimized for harmonic attenuation, while signals from the second band group pass through the circuit optimized for low transmission loss.
2Device complexity
If a single amplification circuit is used for multiple frequency bands, then the device complexity is reduced, but the bandpass characteristics and harmonic attenuation cannot be optimized for each band
Solution Approach 1:
The patent creates a multi-functional amplification system where two amplification circuits share a common switching mechanism and output stage. Each circuit is specialized for specific frequency bands, but together they provide comprehensive coverage with optimized performance for each band group, achieving both specialization and system integration.
3Object-generated harmful factors
If the filter circuit in the subsequent stage is used for harmonic attenuation, then the attenuation can be achieved, but the bandpass characteristics of the high frequency transmission signals cannot be sufficiently improved
Solution Approach 1:
The patent performs harmonic attenuation at the source - in the first amplification circuit before the signal reaches the subsequent filter stage. By addressing harmonic generation early in the signal path, the system prevents harmonic contamination from affecting the bandpass characteristics of subsequent filtering operations.
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 attenuates harmonics of high frequency signals while minimizing transmission loss, enabling efficient simultaneous transmission of multiple frequency bands with improved bandpass characteristics and impedance matching.
Implementation Method 1
the first output matching circuit includes a low-pass circuit in which the first band is set as a pass band and the frequency of the harmonic is set as an attenuation band
Implementation Method 2
the second output matching circuit includes an impedance-variable circuit configured to vary impedance in a pass band in response to the second band and the third band
Implementation Method 3
a first transmission amplification circuit configured to amplify a high frequency transmission signal of a first frequency band group
Implementation Method 4
a second transmission amplification circuit configured to amplify a high frequency transmission signal of a second frequency band group
Data Source
AI summary
A high frequency amplification circuit includes transmission amplification circuits 11 and 12; a transmission filter D-Tx whose pass band is a band D of a first frequency band group; transmission filters E-Tx and G-Tx whose pass bands are respectively bands E and G of a second frequency band group; an output matching circuit 31 configured to match the transmission amplification circuit 11 and the transmission filter D-Tx; and an output matching circuit 32 configured to match the transmission amplification circuit 12 and the transmission filters E-Tx and G-Tx. The band D is positioned at a high frequency-side end portion of the first frequency band group, and the band E is positioned at a low frequency-side end portion of the second frequency band group. The output matching circuit 31 includes a low-pass circuit, and the output matching circuit 32 includes an impedance-variable circuit.