Digital Phase-Frequency Detector for Oscillator Clock Locking
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Solution Overview
Problem
Existing communication systems face challenges in accurately synchronizing high-frequency transmitter oscillators with low-frequency reference clock signals, leading to inconsistencies that complicate locking mechanisms and require complex analog circuit designs difficult to verify with standard tools.
Innovation Solution
A digital phase-frequency detector using mod-M and mod-N counters, along with a count evaluation digital circuit, generates a control signal to adjust the transmitter oscillator's frequency by comparing reference and local clock cycles based on a predefined fixed ratio, facilitating synchronization in the frequency domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If analog circuit designs are used for locking mechanisms, then synchronization between high-frequency transmitter oscillators and low-frequency reference clock signals can be achieved, but the design complexity increases and verification with standard tools becomes difficult
Solution Approach 1:
The patent replaces analog locking mechanisms with a digital phase-frequency detector that uses digital counters and logic circuits. The digital circuit counts reference clock cycles and transmitter oscillator cycles, comparing them to determine frequency and phase relationships. This substitution of digital for analog systems reduces design complexity while maintaining synchronization accuracy, and enables verification with standard digital design tools.
2Reliability
If complex analog locking mechanisms are implemented, then frequency synchronization can be achieved, but the design becomes difficult to verify with standard tools
Solution Approach 1:
The patent implements a digital verification mechanism where the phase-frequency detector outputs a digital verify signal that can be directly measured and verified using standard digital logic analyzers and simulation tools. The digital counters and logic circuits produce measurable digital signals that facilitate easy verification, replacing the难以测量的 analog signals from traditional analog locking mechanisms.
3Reliability
If high-frequency transmitter oscillators are locked to low-frequency reference clocks, then synchronized communication can be achieved, but the locking mechanism becomes complex
Solution Approach 1:
The patent segments the locking mechanism into distinct digital functional blocks: a reference clock counter that counts reference clock cycles, a transmitter oscillator counter that counts oscillator cycles, and a comparison logic unit that determines frequency relationships. This segmentation into modular digital components simplifies the overall design while achieving reliable synchronization between high-frequency oscillators and low-frequency reference clocks.
Solution Approach 2:
The patent replaces the traditional analog phase-locked loop (PLL) locking mechanism with a digital phase-frequency detector that uses digital counting and comparison. This digital substitution simplifies the locking mechanism by using straightforward counter and logic circuit designs rather than complex analog components, while maintaining the ability to lock high-frequency oscillators to low-frequency reference clocks for synchronized communication.
Data Source
AI summary
Methods and apparatuses are provided for locking a transmitter oscillator to a reference clock signal in a frequency domain. The apparatus includes a digital phase-frequency detector. The digital phase-frequency detector includes a mod-M counter, a mod-N counter, and a count evaluation digital circuit. The mod-M counter is designed to count reference clock cycles of a reference clock signal. The mod-N counter is designed to count local clock cycles of a local clock signal. The count evaluation digital circuit is designed to compare the counted reference clock cycles and the local clock cycles with a predefined register setting to generate a control signal as a feedback signal. The control signal is transmitted to the transmitter oscillator through a frequency-locked loop circuit for adjusting the frequency of the transmitter oscillator to be consistent with the reference clock signal.