Oscillator Phase Shifting to Cancel RF Remodulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
RF coupling between the power amplifier and oscillator in wireless transmitters leads to oscillator remodulation, particularly in transmitters with integrated circuits, causing phase or frequency modulation and affecting signal quality.
Innovation Solution
A phase shifting circuit is introduced between the signal generator and amplifier to cancel remodulation by shifting the phase of the signal, with an optional controller to adjust the phase shift based on distortion measurements and maintain constant output power, optimizing the phase delay for improved signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the power amplifier and oscillator are manufactured in the same integrated circuit to reduce device complexity, then manufacturing precision and integration are improved, but oscillator remodulation increases due to RF coupling between the amplifier and oscillator
Solution Approach 1:
A phase shifting circuit is introduced as an intermediary component between the signal generator and power amplifier. This circuit modifies the phase of the amplified signal to create destructive interference with the parasitic feedback signal, thereby canceling the remodulation effect while maintaining the integrated circuit architecture
Solution Approach 2:
The phase shifting circuit applies a preliminary phase adjustment to the signal before amplification, such that the amplified signal's phase is预先 set to counteract the remodulation that will occur during amplification. This preemptive phase shifting creates opposition to the harmful feedback effect
2Object-affected harmful factors
If phase shifting is applied to cancel remodulation, then signal quality is improved, but device complexity increases due to additional circuit components
Solution Approach 1:
The phase shifting circuit changes the phase parameter of the signal to achieve remodulation cancellation. By adjusting this single parameter (phase) rather than redesigning the entire transmitter architecture, the solution improves signal quality with minimal added complexity
Solution Approach 2:
The phase shifting circuit serves as a relatively simple intermediary component that mediates between the signal generator and power amplifier, providing the necessary phase adjustment without requiring complex additional circuitry
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 phase shifting circuit effectively reduces or eliminates remodulation, improving signal quality by minimizing frequency deviation and distortion, even in the presence of IC process variations and temperature changes.
Implementation Method 1
a phase shifting circuit coupled between the signal generator and the amplifier and arranged to shift the phase of the signal to cancel remodulation of the signal generator by the amplified signal
Implementation Method 2
oscillator remodulation can occur because of RF coupling between the power amplifier and the oscillator
Data Source
AI summary
A wireless transmitter (100) comprises a signal generator (10) for generating a signal, an amplifier (50) for amplifying the signal, and a phase shifting circuit (20) coupled between the signal generator (10) and the amplifier (50) and arranged to shift the phase of the signal to cancel remodulation of the signal generator (10) by the amplified signal.