Multi-phase Vector Synthesis Demodulator for Signal Quality
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Solution Overview
Problem
Conventional I/Q demodulators are not optimal for minimizing distortion and interference in heavily impaired received signals in communication systems.
Innovation Solution
A multi-phase vector synthesis method and apparatus using N number of mixers, where N is an odd number greater than or equal to 3, to generate phase-shifted carrier signals, produce mixed signals, and synthesize in-phase and quadrature-phase signals through zero-force synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional I/Q demodulation is used, then the demodulation process is simple, but the distortion and interference in heavily impaired received signals cannot be minimized
Solution Approach 1:
The patent divides the demodulation process into multiple phases by using N mixers (where N≥3) to generate N phase-shifted carrier signals instead of the conventional 2 mixers. This segmentation into multiple parallel demodulation paths allows each mixer to process a specific phase component, enabling the system to handle channel impairments more effectively while maintaining overall system manageability through modular architecture
Solution Approach 2:
The patent combines the outputs of N mixers and N band-pass filters into a unified signal processing chain that feeds into a single in-phase and quadrature-phase signal generation mechanism. By merging the results from multiple parallel processing paths, the system achieves superior signal quality and orthogonality maintenance under channel impairments while consolidating complexity into an integrated demodulation architecture
2Measurement precision
If N number of mixers (N≥3) are used for multi-phase demodulation, then the extraction of in-phase and quadrature-phase signals is improved, but the device complexity increases
Solution Approach 1:
The patent designs the N mixers to serve multiple functions: each mixer not only demodulates a specific phase component but also contributes to the overall orthogonality maintenance and interference rejection. The band-pass filters are configured to handle multiple frequency components simultaneously, and the final signal synthesis mechanism processes all N phase components into the final I and Q signals, making the entire system highly efficient despite the increased number of components
Solution Approach 2:
The patent utilizes phase shifting as a key parameter change mechanism, where N carrier signals are generated with specific phase differences (360°/N between adjacent phases). This parameter change enables the system to distinguish between different signal components more accurately. Additionally, the band-pass filter frequencies are optimized based on the phase shift parameters, allowing the system to maintain high signal extraction accuracy while managing the complexity introduced by multiple mixers
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 multi-phase vector synthesis demodulator significantly improves the extraction of in-phase and quadrature-phase signals, maintaining orthogonality and robustness even under various channel impairments such as non-linear distortion, DC offsets, and interference.
Implementation Method 1
producing N-phase mixed signals by mixing a received signal with N number of phase-shifted carrier signals at N number of mixers
Implementation Method 2
band-pass filtering the N-phase mixed signals and obtaining N-phase demodulated baseband signals by filtering out carrier signal components
Data Source
AI summary
An N-phase vector synthesis demodulator employing N number of mixers is presented. The received signal is mixed with locally generated N number of phase-shifted carrier signals at the N mixers, the individual phases of which are successively and equally 360°/N shifted. The final in-phase (I) and quadrature-phase (Q) signals are zero-force synthesized from the demodulated N-phase vector signals. Compared with the conventional I/Q demodulator that obtains the I and Q signals directly from two mixers of 0° and 90° carrier signal phases, the multi-phase demodulator provides significantly high linearities in the demodulated I and Q signals as the zero-force synthesizer performs an optimal combining of the N-phase demodulated signals while minimizing distortions, interferences, and noise.