Variable-Duty Reference Oscillator for Harmonic Suppression
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Solution Overview
Problem
Conventional reference oscillators in radio frequency receivers suffer from harmonic pollution due to parasitic coupling of higher harmonics, which reduces receiver sensitivity, and existing solutions require lengthy setup times to adjust duty cycles.
Innovation Solution
A reference oscillator with an adjustment circuit that deterministically sets a predefined duty cycle for the reference signal upon activation, minimizing harmonic components by using predefined adjustment parameters, eliminating the need for setup time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the duty cycle is adjusted step-by-step to minimize harmonics, then harmonic pollution is reduced, but setup time increases
Solution Approach 1:
The patent pre-calculates and stores optimal duty cycle values for different operating conditions in a lookup table during the design phase. When the receiver operates, the system simply retrieves the pre-determined duty cycle value corresponding to the current frequency band, eliminating the need for time-consuming real-time iterative adjustments while still achieving harmonic minimization.
Solution Approach 2:
The patent changes the approach from iterative parameter adjustment to direct parameter selection based on pre-established relationships. By storing optimal duty cycle values in a lookup table indexed by operating conditions, the system directly selects the appropriate parameter without requiring time-consuming trial-and-error adjustments, thus resolving the contradiction between harmonic reduction and setup time.
2Ease of manufacture
If the duty cycle is fixed according to production conditions, then manufacturing is simpler, but harmonic minimization is ineffective
Solution Approach 1:
The patent transforms the static, fixed duty cycle approach into a dynamic system that adapts to different operating conditions. By implementing a lookup table that provides different optimal duty cycle values based on the current operating frequency or band, the system maintains manufacturing simplicity while achieving effective harmonic minimization through adaptive parameter selection.
Solution Approach 2:
The patent pre-determines optimal duty cycle values for various operating conditions during the design phase and stores them in a lookup table. This preliminary action allows the system to simply retrieve the appropriate value during operation without requiring complex real-time calculations or iterative adjustments, thus maintaining ease of manufacture while achieving harmonic minimization.
Data Source
AI summary
A reference oscillator for a transmitter and/or a receiver of electromagnetic signals. The reference oscillator is suitable for generating a modified reference signal alternating ON times and OFF times with a predefined duty cycle from a signal supplied by a reference resonator. The reference oscillator also includes an adjustment circuit suitable for adjusting the duty cycle of the modified reference signal according to at least one adjustment parameter dependent on a rank of at least one harmonic component of the modified reference signal so as to minimize at least one harmonic component of the modified reference signal. A frequency synthesizer and a radio frequency signal receiver can include such a reference oscillator.