Clock Data Recovery Band Selection Without Reference Clock Training
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional clock data recovery devices require an accurate reference clock to compensate for clock skew, which can be impractical and costly, and also need a training pattern for accurate data recovery.
Innovation Solution
A clock data recovery device that automatically selects an operating frequency band from multiple frequency bands using a control method involving a phase detector, charge pump, low-pass filter, multi-bands voltage-controlled oscillator, and control module, allowing for blind search or other algorithms to find the optimal frequency band without a precise reference clock or training pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an accurate reference clock is used to compensate clock skew, then the recovery clock accuracy is improved, but the manufacturing cost and device complexity increase
Solution Approach 1:
The clock data recovery device performs self-calibration by using its own output signals as test inputs. The control module feeds back the recovered clock signal to the phase detector and adjusts the VCO frequency automatically without requiring an external reference clock, enabling the system to calibrate itself
Solution Approach 2:
The patent uses a copied version of the output clock signal as the test input signal. By copying the recovered clock signal and feeding it back through the phase detector, the system creates a self-test loop that eliminates the need for an external reference clock while maintaining calibration accuracy
2Measurement precision
If an accurate reference clock is used to compensate clock skew, then the data recovery accuracy is improved, but the manufacturing cost increases
Solution Approach 1:
The system performs self-calibration using internal feedback mechanisms. The control module uses the recovered data and clock signals to automatically adjust the VCO frequency and phase, eliminating the need for expensive external reference clocks and reducing manufacturing costs
Solution Approach 2:
The patent replaces expensive, high-precision reference clocks with a self-calibrating system that uses standard components. The system achieves comparable accuracy through software-based frequency adjustment and phase detection algorithms rather than hardware-based reference clocks
3Measurement precision
If a training pattern is used for accurate data recovery, then the data recovery accuracy is improved, but the transmission time increases
Solution Approach 1:
The system performs preliminary frequency calibration during the self-calibration process before actual data transmission begins. The control module pre-adjusts the VCO frequency based on the detected frequency offset, so that when real data transmission starts, the system is already synchronized and ready for immediate accurate recovery without requiring training patterns
Solution Approach 2:
The system automatically performs frequency offset detection and correction using the received data stream itself. The control module continuously monitors the recovered data quality and adjusts the VCO frequency in real-time without requiring external training sequences, enabling accurate recovery from the start of transmission
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
Enables accurate recovery clock generation and retimed data output without the need for a low jitter reference clock or training pattern, reducing manufacturing costs and improving operational efficiency.
Implementation Method 1
a voltage-controlled oscillator for generating the recovery clock according to the locking voltage
Implementation Method 2
a charge pump, coupled to the phase detector for generating a current signal according to the phase difference signal
Data Source
AI summary
A control method utilized in a clock data recovery device supporting a plurality of frequency bands, for controlling the clock data recovery device to select an operating frequency band from the plurality of frequency bands and to generate a recovery clock for generating retimed data, includes receiving a serial data stream with a data frequency; making each frequency band of the plurality of frequency bands correspond to a plurality of frequency band groups, wherein each frequency band group includes at least one frequency band and corresponds to different frequency ranges; selecting a frequency band group from the plurality of frequency band groups as a coarse-tuned frequency band group according to the data frequency and a locking voltage range; and selecting a frequency band from the plurality of frequency bands according to the data frequency, the locking voltage range and the coarse-tuned frequency band group for generating the recovery clock.