Sampling PLL Oscillator With Frequency Multiplier for Fine Tuning
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Solution Overview
Problem
Existing phase locked oscillators are limited in frequency selection, as they can only generate frequencies that are integer multiples of the reference frequency, restricting their application in communication and radar systems.
Innovation Solution
An analog phase locked oscillator design incorporating a sampling phase detector, loop filter, voltage controlled oscillator, and a frequency multiplier in a feedback loop, allowing for discrete phase comparison and enabling the generation of frequencies that are sub-harmonics of the reference frequency through a non-linear electric circuit module, such as a transistor or diode-based multiplier circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a frequency multiplier is added to the feedback loop, then the output frequency range and resolution are improved, but the device complexity increases
Solution Approach 1:
The frequency multiplication function is segmented into a separate dedicated module within the feedback loop, allowing the VCO to operate at a lower base frequency while the multiplier generates the required higher output frequencies. This segmentation enables flexible frequency selection without redesigning the entire oscillator circuit.
Solution Approach 2:
The frequency multiplier module serves multiple functions: it expands the output frequency range, enables sub-harmonic generation, and maintains phase coherence with the reference frequency. This multi-functional component resolves the contradiction by providing enhanced adaptability without proportionally increasing overall system complexity.
2Ease of operation
If integer multiples of reference frequency are used, then the phase locking is simplified, but the frequency selection capability is limited
Solution Approach 1:
The frequency multiplier acts as an intermediary between the VCO operating at integer multiples of the reference frequency and the desired output frequencies. It translates the simplified integer-multiple frequencies into a broader range of output frequencies, maintaining phase locking simplicity while expanding frequency selection capability.
Solution Approach 2:
By changing the multiplication factor parameter in the frequency multiplier, the output frequency can be adjusted continuously across a wide range while the VCO maintains its simple integer-multiple phase locking relationship with the reference frequency. This parameter change approach resolves the contradiction between operational simplicity and frequency versatility.
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
This design provides a wider range of output frequency choices with higher resolution, reducing phase noise and enabling finer frequency selection, thereby enhancing the utility of phase locked oscillators in communication and radar applications.
Implementation Method 1
the voltage controlled oscillator comprises an acoustic wave component, for example a surface acoustic wave component
Implementation Method 2
the signal frequency multiplier comprises a non-linear electric circuit module
Data Source
AI summary
There is provided an analog phase locked oscillator comprising a sampling phase detector, a loop filter, a voltage controlled oscillator, a frequency multiplier and a feedback loop where the feedback loop connects the output of said oscillator with the input of said phase detector through said frequency multiplier. The sampling phase detector is adapted to perform a discrete phase comparison between a reference frequency and the multiplied feedback signal. The voltage controlled oscillator is adapted to give out a constant frequency at a multiply of the reference frequency divided with the multiplication factor of the multiplier.