Voltage-Mode RF Power Combining Amplifier With Selective Bias Switching

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Solution Overview

Problem

Conventional RF power amplifiers face challenges in maintaining linearity at high output power levels, with Class A amplifiers meeting EVM floor requirements only at lower power levels and Class AB/B amplifiers failing to meet these requirements at low to mid power levels.

Innovation Solution

The RF power combining amplifier circuit selectively activates Class A amplifiers for small voltage signals and Class B or C amplifiers for high output power levels, with individual output matching networks to combine power while maintaining low EVM floors and high output power levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If Class A power amplifier is used, then linearity and EVM floor requirements are met at lower power levels, but output power capability is limited

Engineering Contradiction:

ImproveEVM floorVSAvoidoutput power

Core Design Contradiction:

Measurement precisionVSPower

Solution Approach 1:

The power amplifier is divided into multiple parallel amplifier paths (first power amplifier and second power amplifier), each optimized for different operating conditions. The first amplifier handles lower power levels with Class A biasing for optimal linearity, while the second amplifier handles higher power levels with Class AB/B biasing for optimal power output.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The biasing configuration of the amplifiers is dynamically adjusted through selective activation. A switching mechanism selectively connects either the first amplifier or the second amplifier based on the required output power level, allowing the system to adapt its operating mode to maintain optimal EVM performance across the entire power range.

Inventive Principle:

Principle #15Dynamics

2Power

If Class AB/B power amplifier with gain expansion is used, then high output power requirements are met, but EVM floor requirements are not met at low to mid power levels

Engineering Contradiction:

Improveoutput powerVSAvoidEVM floor

Core Design Contradiction:

PowerVSMeasurement precision

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different amplifier classes and biasing configurations are applied to different operating power levels. Class A biasing with lower current is used for low to mid power levels where linearity is critical, while Class AB/B biasing with higher current is used for high power levels where power output is critical, optimizing performance for each specific operating condition.

Inventive Principle:

Principle #3Local quality

3Power

If multiple power amplifiers are combined with transformer, then output power is increased, but device complexity increases

Engineering Contradiction:

Improveoutput powerVSAvoidcircuit complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

Multiple power amplifier outputs are combined through parallel connection with individual output matching networks, eliminating the need for complex transformer-based combining circuits. This merging approach achieves power multiplication while simplifying the overall circuit architecture.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The parallel amplifier configuration serves multiple functions simultaneously: it provides power multiplication, maintains linearity across different power levels, and simplifies the output combining network. Each amplifier path is independently controllable, adding versatility to the system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10320333B2Voltage mode power combiner for radio frequency linear power amplifier

Publication Date: 2019.06.11 SKYWORKS SOLUTIONS INC

AI summary

A radio frequency (RF) power combining amplifier circuit has a circuit input and a circuit output. A first amplifier is connected to the circuit input and to a first bias input. A first output matching network is connected to an output of the first amplifier and to the circuit output. A second amplifier is connected to the circuit input and to a second bias input. A second output matching network is connected to an output of the second amplifier, and to the circuit output. A voltage level of an input signal applied to the circuit input, together with the respective first bias input and the second bias input, selectively activates the first amplifier and the second amplifier.