Reference Oscillator Duty Cycle Tuning for Harmonic Suppression
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Solution Overview
Problem
Conventional reference oscillators in radiofrequency signal receivers suffer from high harmonic interference due to parasitic coupling, which reduces receiver sensitivity, and existing solutions require lengthy setup times to adjust the duty cycle and minimize harmonics.
Innovation Solution
A reference oscillator with an adjustment circuit that sets a predefined duty cycle for the modified reference signal based on specific parameters, allowing immediate harmonic minimization upon activation, without the need for setup time, using a phase-locked loop and user-input parameters to synchronize and adjust the duty cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the duty cycle is adjusted step by step through incremental variations to minimize harmonics, then the harmonic interference is reduced, but the setup time at each activation becomes long
Solution Approach 1:
The patent pre-calculates and stores optimal duty cycle values corresponding to different frequency ranges before the receiver is activated. When the receiver starts, it quickly determines the current frequency range and directly applies the pre-determined optimal duty cycle, eliminating the need for time-consuming step-by-step incremental adjustments while still achieving harmonic minimization
Solution Approach 2:
The system automatically determines the current frequency range and selects the corresponding optimal duty cycle from pre-stored values without requiring manual intervention or iterative adjustment. The receiver self-configures the duty cycle based on its operating conditions, achieving both rapid setup and effective harmonic suppression
2Loss of time
If a conventional reference oscillator is used without duty cycle adjustment, then the setup time is immediate, but high harmonic components interfere with RF signals through parasitic coupling
Solution Approach 1:
Optimal duty cycle values are pre-calculated and stored in memory before the receiver operates. When activation occurs, the system immediately queries the current frequency range and retrieves the corresponding pre-optimized duty cycle value, achieving both immediate activation and effective harmonic suppression without requiring real-time iterative adjustment
Solution Approach 2:
The patent changes the duty cycle parameter of the reference oscillator based on the operating frequency range. By selecting from pre-determined optimal duty cycle values corresponding to different frequency bands, the system eliminates harmonic interference while maintaining immediate activation capability
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 solution effectively minimizes harmonic interference in radiofrequency receivers by adjusting the duty cycle of the reference signal in real-time, ensuring optimal reception without lengthy activation times.
Implementation Method 1
The oscillator also comprises a reference generator coupled to the resonator to produce an initial reference signal, the adjustment circuit being coupled to the reference generator to generate the reference signal modified with a predefined duty cycle from the initial reference signal. The oscillator also comprises a circuit for synchronizing the modified reference signal to an edge of the initial reference signal.
Data Source
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AI summary
The present invention relates to a reference oscillator (20) for a transmitter and/or receiver of electromagnetic signals. The reference oscillator (20) is adapted to generate a modified reference signal (50) alternating ON and OFF times with a predefined duty cycle from a signal provided by a reference resonator (22). The reference oscillator (20) also includes an adjustment circuit (30) adapted to adjust the duty cycle of the modified reference signal (50) according to at least one adjustment parameter dependent on the rank of at least one harmonic component of the modified reference signal (50) so as to minimize at least one harmonic component of the modified reference signal (50). The invention also relates to a frequency synthesizer and a radio frequency signal receiver comprising a reference oscillator (20) according to the invention.