Clock Recovery Feedback for Amplitude-Phase Demodulation
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Solution Overview
Problem
The gap between internal and external data transmission in semiconductors is widened due to restrictions on the number of pins and wiring, leading to errors in clock signal recovery from amplitude-phase-modulated signals without a parallel clock signal, as phase and amplitude fluctuations affect the PLL output.
Innovation Solution
A demodulation apparatus with a clock recovering section, an amplitude and phase detecting section, and a phase difference correcting section that synchronizes the clock signal with the amplitude-phase-modulated signal, correcting oscillation frequency errors to accurately detect and output data corresponding to the signal's level and transition phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If amplitude-phase-modulated signal is used for data transmission without parallel clock signal, then data transmission efficiency is improved, but clock signal recovery accuracy deteriorates due to phase fluctuation
Solution Approach 1:
The patent introduces a phase difference correcting section as an intermediary component between the clock recovering section and the amplitude/phase detecting section. This corrector uses the detected transition phase information to generate a correction signal that compensates for phase fluctuations in the recovered clock signal, thereby maintaining clock recovery accuracy despite the absence of a parallel clock signal.
Solution Approach 2:
The patent implements a feedback mechanism where the transition phase detected from the amplitude-phase-modulated signal is fed back to the phase difference correcting section. This feedback loop allows the system to continuously adjust and correct the clock signal based on the actual phase variations in the transmitted data, ensuring accurate synchronization.
2Quantity of substance
If phase and amplitude modulation is used to transmit multiple bits per period, then data transmission capacity is improved, but signal detection complexity increases
Solution Approach 1:
The patent segments the detection process into distinct functional sections: a clock recovering section for extracting the clock signal, an amplitude and phase detecting section for measuring signal characteristics, and a phase difference correcting section for compensation. This segmentation allows each section to handle a specific aspect of the complex modulation, making the overall detection process more manageable and systematic.
Solution Approach 2:
The patent performs preliminary phase difference correction using the transition phase information before final data detection. By pre-correcting the clock signal based on detected phase variations, the system simplifies subsequent data recovery operations and reduces the complexity of the overall detection process.
Data Source
AI summary
A demodulation apparatus that demodulates an amplitude-phase-modulated signal having a level and a transition phase selected from among a plurality of levels and a plurality of phases according to transmission data, comprising a clock recovering section that receives the amplitude-phase-modulated signal and recovers a clock signal synchronized with the amplitude-phase-modulated signal; an amplitude and phase detecting section that detects, with the clock signal as a reference, the level and the transition phase of the amplitude-phase-modulated signal; a data output section that outputs data corresponding to the level and the transition phase detected by the amplitude and phase detecting section; and a phase difference correcting section that outputs a correction signal for correcting an oscillation frequency of the clock signal output by the clock recovering section, according to the transition phase detected by the amplitude and phase detecting section.