RF Transmitter Feedback Topology for Harmonic Distortion Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional RF transmitter circuits, particularly those with digitally controlled oscillators (DCO) and digital power amplifiers (DPA), suffer from efficiency losses due to harmonic distortion and injection pulling, which limit their performance and power efficiency, especially at low supply voltages.
Innovation Solution
The implementation of a feedback capacitor and a matching network transformer in an inverting configuration within the power amplifier, along with a magnetically coupled coil, to suppress harmonic distortion and mitigate injection pulling by enhancing feedback coupling and controlling the magnetic coupling factor between the DCO and DPA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a digital power amplifier (DPA) is used to reduce supply voltage and power consumption, then power efficiency is improved, but harmonic distortion increases causing injection pulling at the DCO
Solution Approach 1:
The patent converts the harmful harmonic distortion generated by the DPA into a beneficial feedback signal. By tapping the harmonic component and feeding it back through an inverting amplifier, the distortion is canceled at the DCO input, transforming the harmful effect into a solution that maintains both low power consumption and clean oscillator operation
Solution Approach 2:
The patent implements a feedback mechanism where a portion of the DPA output containing harmonic distortion is fed back to the DCO through an inverting amplifier. This feedback loop cancels the harmonic distortion at the DCO input, allowing the system to maintain low power consumption while eliminating the harmful effects of harmonic distortion
2Loss of energy
If the DPA operates at low supply voltage to improve efficiency, then power efficiency is improved, but injection pulling occurs that pulls the DCO operating frequency
Solution Approach 1:
The patent converts the harmful injection pulling effect into a beneficial frequency stabilization mechanism. By feeding back the inverted harmonic signal, the system cancels the frequency pulling effect, allowing low-voltage operation without compromising frequency stability
Solution Approach 2:
The feedback loop captures the harmonic distortion that causes injection pulling and feeds it back in inverted phase. This cancellation mechanism stabilizes the DCO frequency even when the DPA operates at low supply voltage, maintaining both energy efficiency and frequency reliability
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 reduces injection pulling, enhances power amplifier efficiency, and allows the RF transmitter to operate efficiently at low supply voltages while minimizing harmonic distortion, thereby improving the overall performance of the RF circuit.
Implementation Method 1
The capacitor is electrically coupled between a primary winding and a secondary winding of the matching network transformer
Implementation Method 2
a coil magnetically coupled between a primary winding and a secondary winding of the matching network transformer in the power amplifier
Data Source
AI summary
Systems and methods for suppressing and mitigating harmonic distortion in a circuit are disclosed. In one example, a disclosed circuit includes a radio frequency (RF) oscillator and a power amplifier. The RF oscillator is configured to generate an RF signal. The power amplifier is configured to generate an amplified RF signal based on the RF signal. The power amplifier includes a transformer including a primary winding and a secondary winding, and a feedback capacitor electrically coupled to the primary winding and the secondary winding.