Sweep Frequency Circuit with Multi-Band Switching for Low-Noise Scans
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Solution Overview
Problem
Current sweep frequency signal generation methods struggle to achieve quick sweeping over a wide frequency band while maintaining a high pure spectrum with low noise, which is essential for millimeter wave imaging systems.
Innovation Solution
A circuit comprising a reference frequency source, multiple frequency combination circuits operating on different frequency bands, and a multiple-level switch controlled by a control circuit to alternately output sweep frequency signals across various frequency bands, enhancing sweeping speed and extending frequency width while maintaining low noise levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single frequency synthesizer is used to generate sweep frequency signal, then the circuit structure is simple, but the frequency band is limited and sweeping speed is slow
Solution Approach 1:
The patent divides the frequency synthesizer into multiple parallel units (first frequency synthesizer, second frequency synthesizer, etc.), each operating on a different frequency band. This segmentation allows simultaneous operation across multiple bands, significantly increasing sweeping speed while keeping each individual synthesizer unit relatively simple in structure.
2Object-affected harmful factors
If the sweeping time is extended to reduce noise, then the noise level decreases, but the sweeping speed becomes slow
Solution Approach 1:
The patent implements periodic switching between multiple frequency synthesizer units through a switching network. Each unit operates for a specific time period, and the switching control circuit alternates between them. This periodic action allows the system to achieve low noise levels (by allowing sufficient locking time for each unit) while maintaining fast overall sweeping speed (by parallelizing operations across multiple units).
3Adaptability or versatility
If multiple frequency synthesizers operating on different frequency bands are used, then the frequency band width is extended and sweeping speed is improved, but the circuit structure becomes complex
Solution Approach 1:
The patent designs multiple frequency synthesizer units with identical internal structures, each capable of operating independently on its designated frequency band. This universal design allows the system to achieve wide frequency band coverage and fast sweeping speed through parallel operation, while the modular nature of the design actually simplifies the overall system architecture compared to a single complex synthesizer attempting to cover all bands.
4Adaptability or versatility
If a signal frequency combiner is used, then the frequency band can be extended, but the sweeping speed cannot be improved and noise level remains high
Solution Approach 1:
The patent employs multiple frequency synthesizer units that perform preliminary frequency generation actions in parallel before the final signal combination. Each synthesizer unit pre-generates its frequency signal independently with proper locking time, and then the switching network combines these pre-prepared signals. This preliminary action by multiple units simultaneously enables both extended frequency band coverage and improved sweeping speed, overcoming the limitations of sequential combiner-based approaches.
Data Source
AI summary
A circuit to generate a sweep frequency signal that includes a reference frequency source to generate a reference frequency signal, a first frequency combination circuit coupled to the reference frequency source, and operative to generate a sweep frequency signal in a first frequency band based on the reference frequency signal, a second frequency combination circuit coupled to the reference frequency source, and operative to generate a sweep frequency signal in a second frequency band different from the first frequency band based on the reference frequency signal, a multiple-level switch coupled to outputs of the first frequency combination circuit and the second frequency combination circuit, and a control circuit controlling the first and second frequency combination circuits and the multiple-level switch to output the sweep frequency signal in the first frequency band and the sweep frequency signal in the second frequency band at an output of the multiple-level switch alternately.