Complex-Weighted Continuous-Time Filters for Broadband TX-RX Isolation
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Solution Overview
Problem
Current signal processing technologies face challenges in independently controlling gain, phase, and delay over broadband frequencies, particularly in full-duplex radios where TX signal leakage affects RX signal purity, and existing analog signal processing techniques are limited in combining these tasks effectively.
Innovation Solution
A method and apparatus that split an input signal into multiple paths, allowing for complex weighting to independently control gain, phase, and delay, using a combination of attenuators, delay elements, and filters to sum the outputs, enabling flexible broadband signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional separate attenuator, phase shifter, and delay circuits are used, then each function can be adjusted independently, but the overall system complexity increases and broadband performance is limited
Solution Approach 1:
The patent combines multiple signal processing functions (attenuation, phase shifting, delay) into a single complex-weighting filter structure. Instead of using separate attenuator, phase shifter, and delay circuits, the invention implements all these functions through complex weighting coefficients applied to filtered signal paths, thereby reducing the number of discrete components while maintaining independent control capability.
Solution Approach 2:
The complex-weighting filter serves multiple functions simultaneously: it provides frequency-selective filtering, applies complex weighting for amplitude and phase control, and introduces controlled delay. This multi-functional approach allows a single circuit block to replace what would traditionally require multiple separate components, reducing overall system complexity while maintaining operational flexibility.
2Ease of operation
If multiple separate circuits are used for gain, phase, and delay adjustment, then each parameter can be controlled independently, but the broadband performance deteriorates
Solution Approach 1:
The patent changes the approach from adjusting multiple separate circuit parameters to modifying complex weighting coefficients that are applied to filtered signal paths. By changing the complex weighting parameters, the system can independently control gain, phase, and delay while the frequency-selective filtering ensures broadband performance is maintained across the entire operating frequency range.
3Adaptability or versatility
If DSP is used for signal processing, then complex signal processing tasks can be handled, but analog signal processing is needed for high TX to RX isolation in full-duplex radio
Solution Approach 1:
The patent replaces traditional analog signal processing circuits (attenuators, phase shifters, delay lines) with an analog implementation of complex-weighted filtering that can be controlled by digital coefficients. This hybrid approach allows DSP to generate the complex weighting coefficients while the analog filter circuit performs the actual signal processing, providing high TX to RX isolation in full-duplex radio systems.
4Ease of operation
If traditional analog circuit methods are used for attenuation, phase shifting, and delay, then each function can be implemented, but combining all tasks while maintaining broadband performance is difficult
Solution Approach 1:
The patent segments the signal processing function into multiple parallel filtered paths, each with its own complex weighting coefficient. By dividing the input signal into multiple frequency-selective paths and applying independent complex weights to each, the system can perform multiple signal processing tasks simultaneously while maintaining broadband performance through the frequency-selective filtering characteristic of each path.
Data Source
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AI summary
Various signal processing techniques may benefit from appropriate handling. For example, certain signal processors may benefit from quarter wavelength unit delay and complex weight coefficient continuous-time filters. A method can include splitting an input signal into a plurality of signal paths. The method can also include complex weighting, for each signal path, a respective signal. The method can further include summing outputs of the signal paths. The method can additionally include providing an output comprising the sum of the signal paths. The complex weighting can be configured to independently control gain, phase and delay of the output signal over broadband.