Spread-Spectrum Clock Frequency Level Detection Circuit
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Solution Overview
Problem
Conventional image-reading devices face issues with electromagnetic interference (EMI) and varying data acquisition timing due to the use of spread-spectrum clocks with non-constant clock pulses, which affect the accuracy of image reading processes.
Innovation Solution
A frequency level detecting method and device that count pulses of a spread-spectrum clock within a constant modulation period, dividing the frequency range into sub-ranges corresponding to different frequency levels, and generate a level detection signal to determine the current frequency level of the clock, ensuring accurate timing for data acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a spread-spectrum clock with frequency modulation is used to reduce EMI, then electromagnetic interference is reduced, but data acquisition timing becomes variable and less accurate
Solution Approach 1:
The patent implements a feedback mechanism by detecting the frequency level of the spread-spectrum clock and using this information to adjust the data acquisition timing. The frequency level detection circuit continuously monitors the clock frequency and provides feedback to the timing control circuit, which then compensates for timing variations to maintain accurate data acquisition despite the frequency modulation used for EMI reduction.
2Measurement precision
If a reference clock with constant frequency is used, then data acquisition timing is stable, but electromagnetic interference increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the clock frequency within a controlled range to reduce EMI while maintaining timing accuracy. Instead of using a completely constant frequency, the system modulates the frequency within specific boundaries and uses frequency level detection to ensure that timing-critical operations occur at appropriate frequency levels, thus balancing EMI reduction with timing precision.
3Object-affected harmful factors
If frequency modulation is applied to spread-spectrum clock, then EMI is reduced, but the complexity of timing control increases
Solution Approach 1:
The patent segments the frequency range into multiple discrete frequency levels and corresponds each level with specific timing characteristics. This segmentation allows the timing control circuit to handle different frequency scenarios systematically, reducing overall complexity by breaking down the continuous frequency modulation problem into manageable discrete states that can be addressed with simpler control logic.
Data Source
AI summary
A frequency level detecting method includes counting pulses of a spread-spectrum clock, the spread-spectrum clock having a frequency that is modulated within a frequency range from a minimum frequency to a maximum frequency in a constant modulation period of time, the frequency range being divided into a plurality of sub-ranges each corresponding to one of a plurality of frequency levels; determining at least one to-be-counted value range corresponding to one of the plurality of sub-ranges; judging whether or not the counted pulses fall within one of the at least one to-be-counted value range; and generating a level detection signal if the counted pulses fall within the one of the at least one to-be-counted value range, the level detection signal indicating that a frequency of the spread-spectrum clock falls within one of the plurality of frequency levels that corresponds to one of the plurality of sub-ranges corresponding to the one of the at least one to-be-counted value range.