Variable Frequency Comb Synthesizer for Gap-Free Tuning
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Solution Overview
Problem
Existing synthesizers face limitations in tuning range due to fixed comb lines, resulting in frequency holes and undesirable sinusoidal phase variations caused by mixer non-linearities and spurious signals, which restrict their ability to generate precise frequencies across the desired range.
Innovation Solution
A variable frequency synthesizer design that employs a direct digital synthesizer (DDS) driving a variable frequency comb generator, combined with a phase lock loop (PLL), allowing for continuous tuning and elimination of frequency holes by toggling between two frequencies to achieve desired output frequencies not attainable with fixed settings, using a fixed intermediate frequency and multiple comb lines to cover a broader range without spurious signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fixed comb lines are used in the synthesizer, then the device complexity is reduced and ease of operation is improved, but frequency holes appear in the tuning range and spectral purity deteriorates
Solution Approach 1:
The patent implements variable comb line frequencies that can be dynamically adjusted to fill frequency holes in the tuning range. The comb generator responds to control signals that vary the frequencies of individual comb lines, transforming the static frequency structure into a dynamic one that can adapt to eliminate gaps and maintain continuous tuning coverage.
Solution Approach 2:
The patent changes the frequency parameters of the comb lines from fixed values to variable values. By adjusting the frequencies of individual comb lines based on control signals, the system can fill frequency holes and eliminate spurious responses while maintaining ease of operation through automated control.
2Device complexity
If fixed comb lines are used in the synthesizer, then the device complexity is reduced, but the tuning range coverage is insufficient and frequency holes appear
Solution Approach 1:
The patent transforms the static comb line structure into a dynamic one where individual comb line frequencies can be adjusted. This allows the system to cover the entire desired tuning range continuously by varying comb line frequencies in response to control signals, eliminating frequency holes without significantly increasing device complexity.
Solution Approach 2:
The patent segments the comb generator into individually controllable comb lines. Each comb line can be independently adjusted in frequency, allowing precise control over the frequency spectrum coverage. This segmentation enables the system to fill frequency holes by selectively adjusting specific comb lines rather than requiring a complete redesign.
3Device complexity
If mixer non-linearities and adjacent comb lines are present, then the synthesizer can operate with simple structure, but spurious signals increase and spectral purity deteriorates
Solution Approach 1:
The patent changes the frequency parameters of the comb lines to variable values that can be adjusted to minimize spurious signal generation. By optimizing the frequencies of individual comb lines in response to control signals, the system reduces the impact of mixer non-linearities and eliminates close spurs while maintaining a relatively simple device structure.
Solution Approach 2:
The patent converts the potentially harmful effect of mixer non-linearities into a benefit by using variable comb line frequencies to actively cancel or minimize spurious signal generation. The system adjusts comb line frequencies to optimize performance, turning what would be a limitation into an opportunity for improved spectral purity.
4Manufacturing precision
If variable frequency comb lines are implemented, then frequency holes are eliminated and spectral purity is improved, but the device complexity increases
Solution Approach 1:
The patent introduces a control signal as an intermediary that coordinates the adjustment of multiple comb line frequencies. This intermediary control mechanism allows the system to achieve improved spectral purity and continuous tuning coverage while managing the complexity through centralized control rather than requiring complex individual adjustment mechanisms for each comb line.
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 solution provides a continuous tuning range with no frequency holes, improved spectral purity, and increased flexibility in generating frequencies across the desired range, enhancing the synthesizer's ability to produce precise output frequencies with reduced spurious responses.
Implementation Method 1
a phase lock loop (PLL) receiving the fixed reference frequency and the fixed intermediate frequency and outputting a phase lock signal, the oscillator receiving the phase lock signal
Implementation Method 2
a mixer receiving the variable frequency comb and a signal from an oscillator and outputting a fixed intermediate frequency
Implementation Method 3
a direct digital synthesizer (DDS) receiving the fixed reference frequency and outputting a tuned frequency
Implementation Method 4
the output frequencies of a comb generator are all harmonically related to the input frequency
Data Source
AI summary
A variable frequency synthesizer and method of outputting the variable frequency is disclosed. The synthesizer comprises a first reference frequency, a direct digital synthesizer (DDS) receiving the first reference frequency and outputting a tuned frequency, a variable frequency comb generator receiving the tuned frequency and outputting a variable frequency comb comprised of a plurality of comb lines, a mixer receiving the variable frequency comb and a signal from an oscillator and outputting an intermediate frequency, a phase lock loop (PLL) receiving a second reference frequency and the intermediate frequency and outputting a phase lock signal, and the oscillator receiving the phase lock signal and outputting a variable synthesized frequency.