Low-Voltage Driver RF Power Amplifier With Reduced Interstage Loss

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Solution Overview

Problem

Existing RF power amplifiers face challenges in reducing power consumption and power loss while maintaining efficiency and RF bandwidth, particularly in wireless communication systems where high efficiency is crucial to reduce operational and system costs.

Innovation Solution

The proposed RF power amplifier architecture incorporates a low voltage driver stage and a high voltage final stage, with a significantly reduced impedance transformation ratio between the two stages, allowing for a simpler interstage impedance matching network and reduced losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a conventional two-stage amplifier architecture is used with high voltage driver stage, then sufficient power is delivered to the final stage, but DC power consumption is high and interstage matching losses are significant

Engineering Contradiction:
Improvepower delivery to final stageVSAvoidDC power consumption
Core Design Contradiction:
PowerVSUse of energy by moving object

Solution Approach 1:

The patent changes the voltage parameter of the driver stage from conventional high voltage to low voltage operation. The low voltage driver stage operates at a lower DC voltage level, which directly reduces the DC power consumption (P=VI) while still delivering sufficient power to the final stage through optimized impedance matching and voltage gain in the driver stage.

Inventive Principle:
Principle #35Parameter changes

2Power

If a conventional two-stage amplifier architecture is used with high voltage driver stage, then sufficient power is delivered to the final stage, but interstage matching network losses are significant

Engineering Contradiction:
Improvepower delivery to final stageVSAvoidinterstage matching network losses
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The patent changes the voltage parameter of the driver stage to low voltage, which transforms the impedance characteristics and allows for a lower impedance transformation ratio in the interstage matching network. This reduces the complexity and losses of the matching network, as lower voltage levels with appropriate impedance matching can transfer power more efficiently between stages.

Inventive Principle:
Principle #35Parameter changes

3Use of energy by moving object

If a low voltage driver stage is used, then DC power consumption is reduced, but the ability to deliver sufficient power to the final stage may be compromised

Engineering Contradiction:
ImproveDC power consumptionVSAvoidpower delivery to final stage
Core Design Contradiction:
Use of energy by moving objectVSPower

Solution Approach 1:

The patent employs dynamic voltage gain control in the low voltage driver stage. By optimizing the driver stage design to provide higher voltage gain, the low voltage signal is amplified sufficiently before reaching the final stage, ensuring adequate power delivery despite the lower operating voltage. The impedance matching network is also optimized to maximize power transfer efficiency.

Inventive Principle:
Principle #15Dynamics

4Use of energy by moving object

If a low voltage driver stage is used, then DC power consumption is reduced, but impedance matching complexity may increase

Engineering Contradiction:
ImproveDC power consumptionVSAvoidimpedance matching network complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent changes the impedance parameters of the driver stage output and final stage input to achieve a lower impedance transformation ratio. By designing the low voltage driver stage with optimized output impedance and the final stage with complementary input impedance, the matching network requires smaller transformation ratios, which simplifies the matching network design and reduces component count despite the low voltage operation.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3849078B1Multiple-stage power amplifiers and devices with low-voltage driver stages
Publication Date: 2025.04.09 NXP USA INC
  • EP3849078B1 patent drawingFigure 1
  • EP3849078B1 patent drawingFigure 2
  • EP3849078B1 patent drawingFigure 3

AI summary

An amplifier includes a driver stage amplifier transistor and a final stage amplifier transistor, which are integrated in a semiconductor die. The driver stage amplifier transistor has a driver stage input, a driver stage output, and an output impedance, and the driver stage amplifier transistor is configured to operate using a first bias voltage at the driver stage output. The final stage amplifier transistor has a final stage input, a final stage output, and an input impedance. The final stage input is electrically coupled to the driver stage output. The final stage amplifier transistor is configured to operate using a second bias voltage at the final stage output, and the second bias voltage is at least twice as large as the first bias voltage.