Wideband Doherty Power Amplifier With Active Load Modulation

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Solution Overview

Problem

Current RF power amplifiers face challenges in achieving high efficiency, linearity, and broadband operation due to limitations in bandwidth and parasitic properties, particularly in Doherty amplifiers, which restrict their ability to handle high-power and wide-bandwidth applications effectively.

Innovation Solution

The implementation of a high-power transmitting and receiving device with a Doherty amplifier architecture that includes additional multiharmonic transformation lines and a circulator to protect the amplifiers from overvoltages and overcurrent, along with a digital input signal divider for optimized power and phase control, enabling high relative bandwidth and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a Doherty amplifier architecture is used to increase efficiency, then power efficiency is improved, but bandwidth is limited to 5% to 10%

Engineering Contradiction:

Improvepower efficiencyVSAvoidbandwidth

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The amplifier is divided into multiple amplifier cores (main power amplifier and peak power amplifiers) that operate in different modes. The main amplifier operates in linear mode while peak amplifiers operate in saturated mode, allowing the system to achieve high efficiency across a wide bandwidth by selectively activating different segments based on signal power level.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The amplifier dynamically switches between different operating states by activating or deactivating peak power amplifiers based on the instantaneous signal power level. This dynamic operation allows the system to maintain high efficiency across varying power levels and bandwidth conditions, transitioning from single-amplifier operation to multi-amplifier operation as needed.

Inventive Principle:

Principle #15Dynamics

2Power

If high power amplification is achieved, then transmission power is increased, but linearity deteriorates

Engineering Contradiction:

Improvetransmission powerVSAvoidlinearity

Core Design Contradiction:

PowerVSManufacturing precision

Solution Approach 1:

Different parts of the amplifier system have different operational characteristics optimized for their specific function. The main power amplifier maintains linear operation for accurate signal reproduction, while peak power amplifiers operate in saturated non-linear mode for high efficiency. The combining network integrates these different quality characteristics to achieve both linearity and high power output.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

A combining network acts as an intermediary between the linear main amplifier and the saturated peak amplifiers. This intermediary component properly combines the output signals while maintaining the linear characteristics from the main amplifier and incorporating the high power capability from the peak amplifiers, achieving both linearity and high transmission power.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If broadband operation is implemented, then frequency range is extended, but efficiency decreases

Engineering Contradiction:

Improvefrequency rangeVSAvoidefficiency

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The amplifier system is designed to universally handle multiple frequency ranges and power levels through a single architecture. The combination of main and peak amplifiers with appropriate matching networks enables the system to maintain high efficiency across a broad frequency range by adapting the operating state of different amplifier segments to the specific frequency and power conditions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Reliability

If protection from overvoltages and overcurrent is added, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improveprotection capabilityVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The circulator provides automatic protection by directing excess energy to the sump resistor when overvoltages or overcurrents occur, without requiring external control circuits or complex protection logic. The system self-regulates by using the circulator's inherent directional properties to isolate the amplifiers from damaging conditions, improving reliability while adding minimal complexity.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS11652448B2Transmitting and receiving device having a wide-band HF power amplifier, in particular an N-way Doherty amplifier having active load modulation

Publication Date: 2023.05.16 IAD GESELLSCHAFT FUER INFORMATIK AUTOMATISIERUNG & DATENVERARBEITUNG MBH

AI summary

A transmitting and receiving device having a module (GSZ) with a configurable HF high-power amplifier (HPA) that includes a main power amplifier (DM) with a main amplifier core and at least one peak power amplifier (DP1) having an auxiliary amplifier core. A switching element connected to inputs of the main power amplifier and the at least one peak power amplifier is connected to a digital input signal divider (ET) having a plurality of outputs and an output combiner (C) is connected to outputs of the amplifier cores for the main power amplifier and the at least one peak power amplifier. A multi-harmonic transformation line (LAH) is connected at the amplifier core output of the main power amplifier and at the amplifier core output of the at least one peak power amplifier, and a circulator (Z1) is connected to the output of the output combiner or an impedance converter (AN1).