Hybrid PLL Frequency Generator for Stable Low-Cost Signal Control
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Solution Overview
Problem
Current frequency signal generating systems face challenges in achieving precise control and stability while being cost-effective, with analog devices offering low stability and digital synthesis devices being expensive.
Innovation Solution
A closed-loop frequency signal generating system combining analog and digital circuits, utilizing a digital phase-locked loop, voltage controlled oscillator, and negative feedback circuit to produce precisely controllable target frequency signals, reducing costs through the integration of analog and digital components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an analog device is used to generate frequency signals, then the cost is low, but the stability and precision of the generated frequency signals are poor
Solution Approach 1:
The patent combines analog circuits (VCO, loop filter) with digital circuits (phase-locked loop, frequency divider) to create a hybrid frequency signal generating system. This merging allows the system to achieve the stability of digital systems while maintaining lower costs compared to pure digital synthesis devices.
Solution Approach 2:
The patent implements a negative feedback mechanism where the generated frequency signal is fed back through a frequency divider to the phase detector, which compares it with the reference signal and adjusts the VCO accordingly. This feedback loop significantly improves the stability and precision of the generated frequency signals.
2Measurement precision
If a digital synthesis device is used to generate frequency signals, then the precision and stability are improved, but the cost increases significantly
Solution Approach 1:
The patent merges analog VCO technology with digital phase-locked loop technology, achieving precise frequency control through digital means while using analog components that are more cost-effective than full digital synthesis devices.
Solution Approach 2:
The patent uses relatively simple and cost-effective analog components (VCO, loop filter) combined with digital logic, avoiding the need for expensive dedicated digital synthesis chips or FPGAs, thereby reducing the overall system cost while maintaining precision.
3Manufacturing precision
If an analog device is used to generate frequency signals, then the cost is low, but the frequency step control precision is insufficient
Solution Approach 1:
The phase detector in the feedback loop detects phase differences between the reference signal and the divided feedback signal, enabling precise control of frequency steps by adjusting the VCO control voltage based on the detected phase error.
Solution Approach 2:
The patent replaces mechanical or purely analog frequency control methods with digital phase detection and control, allowing for precise frequency step control through digital counting and comparison mechanisms in the phase-locked loop.
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
The system generates accurately controlled frequency signals with improved stability, reducing costs by leveraging the combination of analog and digital circuits, and facilitating easy monitoring through a human-computer interface.
Implementation Method 1
a voltage controlled oscillator, an input terminal of which is connected to an output terminal of the loop filter, for outputting a target frequency signal according to a signal from the loop filter
Implementation Method 2
a loop filter, an input terminal of which is connected to an output terminal of the digital phase-locked loop, for filtering out high frequency components of a signal output from the digital phase-locked loop
Implementation Method 3
the digital phase-locked loop performs frequency-dividing and phase-detecting on the source frequency signal and the fed back target frequency signal
Implementation Method 4
the digital phase-locked loop performs frequency-dividing and phase-detecting on the source frequency signal and the fed back target frequency signal
Implementation Method 5
the system uses a negative feedback circuit to improve the stability of the system; an output terminal of the voltage controlled oscillator is connected to a first input terminal of the digital phase-locked loop so that the target frequency signal output from the voltage controlled oscillator is fed back to the digital phase-locked loop
Data Source
AI summary
A frequency signal generating system comprises a digital phase-locked loop for receiving a source frequency signal; a loop filter for filtering out high frequency components of a signal output from the digital phase-locked loop; and a voltage controlled oscillator for outputting a target frequency signal according to a signal from the loop filter, wherein an output terminal of the voltage controlled oscillator is connected to a first output terminal of the digital phase-locked loop so that the target frequency signal output from the voltage controlled oscillator is fed back to the digital phase-locked loop, the digital phase-locked loop performs frequency-dividing and phase-detecting on the source frequency signal and the fed back target frequency signal so that the target frequency signal output from the voltage controlled oscillator and the source frequency signal satisfy a definite mathematical relationship therebetween.