Outphasing Amplifier Using Phase Mapping for Linear SMPA Output

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Solution Overview

Problem

Existing amplifiers face efficiency and linearity issues when handling high peak-to-average-power ratio signals, particularly with switched-mode power amplifiers (SMPAs), due to inefficiencies in outphasing architectures and quantization noise in sigma-delta based solutions.

Innovation Solution

An amplifier design that converts input signals to quantized samples using oversampling, maps these samples to constant-envelope phase-modulated signals, and combines them using power amplifiers for efficient amplification, minimizing quantization noise and complexity through phase mapping and combiner alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If linear power amplifiers are used to amplify amplitude modulated signals, then linearity is maintained, but power efficiency decreases significantly

Engineering Contradiction:

ImprovelinearityVSAvoidpower efficiency

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent segments the amplitude modulated signal into two constant-envelope phase-modulated signals through signal component separation. These segmented signals are then processed separately by SMPAs, allowing the use of non-linear amplifiers while maintaining overall signal fidelity through subsequent recombination.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary signal component separator (SCS) that converts the amplitude modulated signal into constant-envelope phase-modulated signals. This intermediary transformation enables the use of SMPAs by eliminating amplitude variations that would otherwise cause non-linearity issues.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If switched-mode power amplifiers are used for direct amplification of amplitude modulated signals, then power efficiency reaches theoretical maximum, but linearity is lost due to strong non-linearity

Engineering Contradiction:

Improvepower efficiencyVSAvoidlinearity

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

Instead of attempting to linearize the SMPA output, the patent inverts the approach by pre-processing the input signal to eliminate amplitude variations. The amplitude modulated signal is converted into constant-envelope signals before amplification, so the non-linear SMPA operation does not distort the amplitude information.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the signal parameters by transforming the amplitude-modulated signal into constant-envelope phase-modulated signals. This parameter transformation allows SMPAs to operate in their efficient non-linear regime while the signal structure ensures that amplitude information is preserved through phase relationships.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If outphasing architecture with signal component separator is used, then SMPAs can be utilized, but efficiency loss increases with increasing outphasing angles

Engineering Contradiction:

Improvepower efficiencyVSAvoidefficiency loss

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The patent employs dynamic signal component separation that adapts to the input signal characteristics. By dynamically adjusting the separation based on the instantaneous signal conditions, the system maintains optimal outphasing angles and minimizes efficiency losses that would otherwise increase with larger fixed outphasing angles.

Inventive Principle:

Principle #15Dynamics

4Device complexity

If sigma-delta modulator with two quantization levels is used, then constant envelope signal is generated, but coding efficiency is poor and quantization noise is significant

Engineering Contradiction:

Improvequantization levelsVSAvoidquantization noise

Core Design Contradiction:

Device complexityVSLoss of information

Solution Approach 1:

The patent transitions from single-bit quantization to multi-level quantization, adding an additional dimension to the signal representation. By using multiple quantization levels for the in-phase and quadrature components, the system reduces quantization noise while maintaining constant-envelope properties suitable for SMAA amplification.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS20250364954A1amplifier

Publication Date: 2025.11.27 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)

AI summary

An amplifier (100) is provided for amplifying a complex input communication signal (109) having an in-phase and quadrature component. The amplifier has a modulation circuitry (110) configured to convert the input signal to quantized samples (111) by performing oversampling, where the quantized samples represent a finite set of constellation points; and a phase mapping circuitry (120) configured to map the quantized samples onto two constant-envelope phase-modulated signals (121, 122) selected from a finite set of constant-envelope phase-modulated signals (172, 221-224) having a carrier frequency fc (171) and (different) constant phases. A first and second power amplifier (130, 140) is configured to amplify the two constant-envelope phase-modulated signals by a gain G; and a combiner (150) is configured to combine the two amplified constant-envelope phase-modulated signals (131, 141) thereby obtaining a complex output communication signal (151) with the carrier frequency fc representing an amplification (161) of the complex input communication signal (109).