Envelope Tracker Supply Network Layout for PA Noise Reflection
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Solution Overview
Problem
In power supply circuits with envelope trackers and power amplifiers, noise signals can cause resonance and radiation, degrading communication characteristics due to the reflection of noise signals between the envelope tracker and power amplifiers.
Innovation Solution
A power supply circuit design incorporating a main inductor on the common line and sub-inductors on branch lines, with the main inductor's cutoff frequency higher than the envelope signal frequency and self-resonant frequencies of sub-inductors set within radio frequency bands, to attenuate noise signals and prevent resonance and radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an inductor for choking is connected to each power amplifier to prevent noise signal from flowing in the power amplifiers, then the noise signal is reflected and prevented from entering the power amplifiers, but the noise signal returns to the envelope tracker and causes resonance in the connection line, leading to noise radiation and deterioration of communication characteristics
Solution Approach 1:
A capacitor is introduced as an intermediary component connected between the envelope tracker output and the inductor. This capacitor provides an alternative path for the reflected noise signal, preventing it from returning to the envelope tracker and causing resonance. The capacitor acts as a mediator that absorbs or redirects the harmful reflected energy, thereby eliminating the noise radiation problem while maintaining the noise blocking function of the inductor.
Solution Approach 2:
The reflected noise signal, which was previously causing harmful resonance and radiation, is converted into a beneficial effect by the capacitor. The capacitor absorbs the reflected noise energy and redirects it to ground or dissipates it, transforming the harmful reflection into a controlled energy pathway that prevents resonance. This converts the problematic noise reflection into a manageable electrical phenomenon that enhances overall system performance.
2Object-affected harmful factors
If a main inductor is provided on the common line and sub-inductors are provided on the branch lines, then the noise signal conducted from the envelope tracker toward each power amplifier is reduced, but the device complexity increases
Solution Approach 1:
The noise filtering function is segmented into two levels: a main inductor on the common line that handles noise at the primary level, and sub-inductors on each branch line that handle noise at the individual amplifier level. This segmentation allows each inductor to be optimized for its specific function and position in the circuit, providing comprehensive noise reduction while maintaining a systematic and organized structure that is easier to design and maintain.
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 configuration effectively reduces noise signals conducted between the envelope tracker and power amplifiers, improving communication characteristics and reception sensitivity by suppressing noise radiation across multiple radio frequency bands.
Implementation Method 1
an inductor for choking is connected to each of the power amplifiers... causes a noise signal leaked from power amplifiers not to flow to the exterior and prevents the noise signal from flowing in the power amplifiers by an inductor
Implementation Method 2
a capacitor provided on the common line... a cutoff frequency of the main inductor is preferably higher than a frequency of the envelope signal
Data Source
AI summary
A power supply circuit includes a plurality of power amplifiers for amplifying radio frequency signals, an envelope tracker for supplying a variable voltage based on an envelope signal to the power amplifiers, a common line connected to an output side of the envelope tracker, and a plurality of branch lines branching from a tip of the common line and connected to the power amplifiers, respectively. On the branch lines, sub-inductors are provided, respectively. On the common line, a main inductor and a capacitor are provided.