Controllable Envelope Tracking Filters for RF Power Amplifiers

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Power amplifiers in RF communication systems face challenges in managing RF signal power efficiently, leading to reduced battery life and inadequate transmit power levels, particularly in devices like mobile phones and base stations, due to inadequate noise filtering and power management.

Innovation Solution

The implementation of a power amplifier module with a controllable envelope tracking system that includes a power amplifier, an envelope tracker generating a supply voltage based on the RF signal envelope, and a controllable filter providing adjustable noise filtering through selectable circuit branches, such as series inductor-capacitor networks, to optimize power efficiency and noise reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If envelope tracking is used to dynamically adjust power amplifier supply voltage, then power added efficiency is improved, but noise filtering becomes more challenging

Engineering Contradiction:

Improvepower added efficiencyVSAvoidnoise filtering

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The filter configuration is made dynamic and adjustable based on operating conditions. The system switches between different filter configurations (first and second configurations) depending on the signal characteristics and power amplifier operating state, allowing optimal noise filtering at different efficiency points.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The filter parameters (impedance, cutoff frequency, etc.) are changed by reconfiguring the circuit topology. The switchable capacitor banks and reconfigurable impedance networks allow the filter characteristics to be adjusted to match different envelope tracking operating modes, resolving the conflict between efficiency improvement and noise suppression.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If fixed filter configuration is used, then device complexity is reduced, but adaptability to different signal characteristics is worsened

Engineering Contradiction:

Improvefilter configurationVSAvoidsignal characteristic adaptation

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The filter transitions from a fixed configuration to a dynamic, reconfigurable system. Multiple switchable capacitor banks and impedance networks allow the filter to adapt its characteristics in real-time based on bandwidth requirements, waveform types, and resource block allocations without significantly increasing overall device complexity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The reconfigurable filter serves multiple functions: it acts as an envelope tracking noise filter, a bandwidth adapter, and a waveform-specific optimizer. By integrating multiple filter configurations into a single reconfigurable module, the system achieves versatility across different signal types while maintaining a compact structure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Object-affected harmful factors

If aggressive noise filtering is applied, then noise reduction is improved, but power added efficiency deteriorates

Engineering Contradiction:

Improvenoise reductionVSAvoidpower added efficiency

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The filter strength is made dynamic rather than fixed. The system adjusts the filter configuration based on the actual noise levels and signal characteristics, applying stronger filtering only when necessary. This prevents continuous efficiency degradation while maintaining adequate noise reduction when required.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The filter parameters are changed to match the operating conditions. By adjusting capacitance values, impedance levels, and cutoff frequencies based on the envelope tracking mode and signal characteristics, the system achieves optimal balance between noise reduction and efficiency for each operating point.

Inventive Principle:

Principle #35Parameter changes

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 enhances power added efficiency (PAE) by dynamically adjusting the power amplifier supply voltage based on RF signal characteristics, offering flexible noise filtering and improved power management, thereby extending battery life and ensuring suitable transmit power levels.

Implementation Method 1

a controllable filter configured to filter the power amplifier supply voltage to provide envelope tracking noise filtering

Methodology Applied

Scientific EffectElectrical filtering: Filter (electronic)

Implementation Method 2

the plurality of circuit branches includes a plurality of series inductor-capacitor networks

Methodology Applied

Scientific EffectInductor-capacitor filtering: Inductor

Data Source

PatentUS12126307B2Power amplifier modules with controllable envelope tracking noise filters

Publication Date: 2024.10.22 SKYWORKS SOLUTIONS INC

AI summary

Power amplifier modules with controllable envelope tracking noise filters are provided herein. In certain embodiments, an envelope tracking system includes a power amplifier module and an envelope tracker that provides the power amplifier module with a power amplifier supply voltage that changes based on an envelope of a radio frequency (RF) signal amplified by the power amplifier module. The power amplifier module includes a controllable filter that filters the power amplifier supply voltage to provide flexibility in filtering envelope tracking noise.