Split-Band Signal Processing for Flat Phase Broadband Amplification
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Solution Overview
Problem
Conventional broadband signal processing systems face limitations in linear signal processing, particularly when handling large bandwidths that extend to low frequencies near or at 0 Hz, due to inferior noise performance, distortion, and efficiency compared to narrowband amplifiers.
Innovation Solution
The implementation of a split band processing system that separates signals into two or more frequency bands for individual processing with optimized circuitry, using diplexers to split and recombine signals while ensuring a transfer function close to unity, with optional time delay and phase shift to maintain flat magnitude and linear phase responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single broadband amplifier is used to handle the entire frequency range from 0 Hz to RF/microwave, then the system complexity is reduced, but the noise performance, distortion, and efficiency deteriorate significantly
Solution Approach 1:
The broadband frequency range is divided into multiple sub-bands using diplexers or filter banks. Each sub-band is then processed by dedicated narrowband amplifiers optimized for specific frequency ranges, rather than using a single broadband amplifier. This segmentation allows each amplifier to operate in its optimal performance region, improving noise performance and reducing distortion while maintaining manageable system complexity through modular architecture.
Solution Approach 2:
Different amplifier types with locally optimized characteristics are assigned to different frequency sub-bands. For example, low-frequency sub-bands may use DC-coupled amplifiers while high-frequency sub-bands use AC-coupled amplifiers with different topologies. Each amplifier is designed with quality specifically tailored to its assigned frequency range, improving overall system performance across the entire broadband spectrum.
2Device complexity
If a single broadband amplifier is used to handle the entire frequency range, then the device count is reduced, but the distortion and efficiency worsen
Solution Approach 1:
The frequency spectrum is segmented into multiple sub-bands, each handled by dedicated amplifiers. This prevents a single amplifier from operating across its entire bandwidth where distortion increases, particularly at frequency extremes. Each narrowband amplifier operates within its optimal range, minimizing distortion and efficiency losses that would occur in a broadband amplifier operating across the full spectrum.
Solution Approach 2:
The operating parameters (frequency range, gain, bandwidth) of amplifiers are changed and optimized for each specific sub-band. Rather than using a fixed broadband amplifier with compromised parameters across the entire range, the system employs multiple amplifiers with parameters tailored to their respective frequency assignments, reducing distortion and improving efficiency.
3Adaptability or versatility
If broadband amplifiers operating near 0 Hz are used, then the frequency coverage is extended, but the noise performance and efficiency deteriorate
Solution Approach 1:
The frequency coverage is segmented into low-frequency and high-frequency sub-bands. Low-frequency sub-bands near 0 Hz are handled by DC-coupled amplifiers optimized for this range, while high-frequency sub-bands are handled by AC-coupled amplifiers. This segmentation allows the system to achieve broad frequency coverage while maintaining high efficiency in each sub-band, avoiding the efficiency deterioration that occurs in broadband amplifiers operating near 0 Hz.
Solution Approach 2:
Different amplifier topologies with locally optimized efficiency characteristics are assigned to different frequency regions. DC-coupled amplifiers with high efficiency are used for low-frequency sub-bands, while other topologies optimized for high-frequency operation are used elsewhere. This local optimization maintains high efficiency across the entire frequency coverage range.
Data Source
AI summary
A split-band system for processing a broadband input signal is disclosed. A signal divider divides the input signal into at least a higher frequency band and a lower frequency band. The lower frequency band is processed in a lower frequency circuit path. The higher frequency band is processed in a higher frequency circuit path. The higher frequency circuit path has a group delay equal to the lower frequency circuit path. A signal combiner combines the processed lower frequency band and the processed higher frequency band into an output signal.