Diplexed Broadband Power Amplifier for Low Intermodulation
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Solution Overview
Problem
Existing signal amplification methods in frequency-hopping radars and communications systems face challenges in achieving broadband amplification with high power-added efficiency (PAE) and maintaining linearity for concurrent signals, as narrowband power amplifiers do not support inter-band carrier aggregation and suffer from signal mixing and harmonic generation.
Innovation Solution
A broadband amplifier design that uses a diplexer to separate broadband input signals into high and low band signals, which are then amplified separately and recombined, employing passive diplexers to minimize signal mixing and intermodulation products, with optional digital pre-distortion for further linearity improvement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single-ended broadband power amplifier is designed to achieve octave or decade bandwidth, then bandwidth is improved, but signal mixing and harmonic generation occur within the active nonlinear device causing intermodulation products
Solution Approach 1:
The broadband amplifier is segmented into multiple narrowband amplifier modules, each handling a specific frequency band. The input signal is divided into multiple frequency bands through diplexers or filters, and each band is amplified by a dedicated narrowband amplifier module. This segmentation prevents signal mixing and intermodulation products while achieving broadband coverage through parallel processing of multiple frequency bands.
2Loss of energy
If a load-modulated balanced amplifier is used to achieve octave bandwidth and high efficiency, then power-added efficiency is improved, but linearity becomes a concern due to signal mixing and harmonic generation
Solution Approach 1:
The amplifier system is divided into multiple independent narrowband amplifier modules, each optimized for a specific frequency band. By segmenting the signal path and using dedicated amplifiers for each band, signal mixing is eliminated while maintaining high efficiency through optimized narrowband designs. The segmented architecture allows each module to operate in its optimal efficiency region without compromising linearity.
3Object-generated harmful factors
If two-dimensional digital pre-distortion algorithms are applied to compensate for signal mixing, then linearity is improved, but complexity in the RF domain is traded for complexity in baseband
Solution Approach 1:
Instead of using complex baseband pre-distortion algorithms, the system segments the broadband signal into multiple narrowband signals that are processed independently by dedicated amplifier modules. This architectural segmentation eliminates signal mixing at its source, achieving linearity without requiring complex digital pre-distortion processing in the baseband domain.
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 achieves high power-added efficiency and improved linearity for concurrent signals by isolating and recombining amplified high and low band signals, reducing intermodulation products and maintaining efficient performance across a broad frequency range.
Implementation Method 1
a first diplexer receiving broadband input signals and divides them by frequency into a low band input signal and a high band input signal
Implementation Method 2
The amplifier has separate high band and low band amplifiers coupled to amplify the low and high band input signals
Implementation Method 3
a second diplexer coupled to combine outputs of the low and high band amplifiers to form a wideband output
Data Source
AI summary
A wideband amplifier includes a first diplexer receiving broadband input signals and divides them by frequency into a low band input signal and a high band input signal. The amplifier has separate high band and low band amplifiers coupled to amplify the low and high band input signals, and a second diplexer coupled to combine outputs of the low and high band amplifiers to form a wideband output. A method of amplification of an input signal includes separating the input signal into high and low band signals, separately amplifying the high and low band signals, and combining amplified high and low band signals into an output signal.