Dual Digital Power Amplifier for Efficiency-Linearity Tradeoff

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Solution Overview

Problem

Power amplifiers in wireless communications devices face a tradeoff between efficiency and linearity, with high efficiency typically occurring at maximum output power but resulting in nonlinear operation, which is inadequate for meeting linearity requirements for signals with large peak-to-average ratios.

Innovation Solution

A power amplifier system using two digital amplifiers, where one amplifier processes the digital input signal to generate an analog output and an adjustment module adjusts amplitude and phase information to control the relationship between the two amplifiers' outputs, allowing for improved efficiency and linearity by combining their signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the power amplifier operates at maximum output power to achieve maximum efficiency, then efficiency is improved, but linearity deteriorates

Engineering Contradiction:

ImproveefficiencyVSAvoidlinearity

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The power amplifier is divided into two separate digital amplifiers operating in parallel. The first digital amplifier handles the fundamental signal component while the second digital amplifier handles the peak signal component. This segmentation allows each amplifier to operate in its optimal region - the first amplifier operates at lower power with high linearity, while the second amplifier activates during peaks to maintain overall efficiency, thus resolving the contradiction between efficiency and linearity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically adjusts the operation of the two digital amplifiers based on the instantaneous signal amplitude. An envelope detector monitors the input signal and controls the activation and gain of the second amplifier accordingly. During low-power periods, only the first amplifier operates; during high-power peaks, the second amplifier is activated. This dynamic operation allows the system to maintain high linearity during normal operation while achieving high efficiency during peak transmission.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If the power amplifier operates well under peak power to maintain linearity for high PAR signals, then linearity is improved, but efficiency deteriorates

Engineering Contradiction:

ImprovelinearityVSAvoidefficiency

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second digital amplifier is designed to operate only partially - it remains inactive during normal signal conditions and activates only during peak signal excursions. This partial operation allows the system to maintain high linearity during the majority of operation time while achieving high efficiency during peak transmission periods, effectively resolving the contradiction between maintaining linearity and achieving efficiency.

Inventive Principle:

Principle #16Partial or excessive action

3Device complexity

If a single digital amplifier is used, then device complexity is reduced, but the ability to simultaneously achieve high efficiency and linearity deteriorates

Engineering Contradiction:

Improveamplifier structureVSAvoidefficiency

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

Two digital amplifiers are merged into a single power amplifier system with a common output stage and control architecture. The amplifiers share common components including the envelope detector, control logic, and output matching network. This merging approach achieves the dual goals of maintaining high efficiency and linearity while minimizing the increase in device complexity through shared resources and integrated control.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The first digital amplifier is designed with multi-functionality to handle both linear amplification during normal operation and to serve as the primary amplifier during low-power conditions. The second amplifier serves multiple functions: providing peak power enhancement, maintaining linearity during high-power operation, and enabling the overall system to achieve high efficiency. This universality reduces the need for additional specialized components, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8981845B1Digital power amplifier

Publication Date: 2015.03.17 MARVELL ASIA PTE LTD

AI summary

Systems and methods for power amplification using multiple digital amplifiers are provided. A power amplifier includes a first digital amplifier configured to process a digital input signal to generate a first analog output signal. The first analog output signal is configured to have a magnitude corresponding to amplitude information of the digital input signal. The power amplifier further includes a second digital amplifier configured to process an adjusted digital input signal to generate a second analog output signal. The second analog output signal is configured to have a magnitude corresponding to amplitude information of the adjusted digital input signal. An adjustment module configured to adjust amplitude information and phase information of the digital input signal generates the adjusted digital input signal. The digital input signal is adjusted to control a relationship between the first analog output signal and the second analog output signal.