Envelope Tracking DC-DC Converter for RF Power Amplification

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The challenge lies in implementing high-efficiency dc-dc converters for envelope tracking techniques in high power RF applications, which require supporting large modulation bands while maintaining efficiency and low cost, as existing solutions either sacrifice efficiency for bandwidth or increase complexity and cost.

Innovation Solution

A system that analyzes the maximum envelope tracking control signal over a time interval and applies a constant supply voltage level from available voltage levels for a minimum duration, generating a discrete power supply signal that changes slowly with modulation band, allowing for low-cost, high-efficiency dc-dc converters even for large modulation bands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a linear amplification part is used in the dc-dc converter to track quick variations of the envelope signal, then the bandwidth is improved, but the overall efficiency is significantly deteriorated due to the low efficiency of the linear amplification part

Engineering Contradiction:

ImprovebandwidthVSAvoidefficiency

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The invention extracts and removes the linear amplification part from the dc-dc converter architecture. Instead of using a linear amplifier to track envelope variations, the patent uses a switching dc-dc converter operating in discontinuous conduction mode, which eliminates the inefficient linear amplification stage while maintaining the ability to track envelope signal variations through capacitive coupling and resonant circuits.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the operating parameters of the dc-dc converter by operating in discontinuous conduction mode rather than continuous mode. This parameter change allows the converter to achieve both high efficiency and high bandwidth performance, as the discontinuous mode enables faster response to envelope variations without requiring a linear amplification stage.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If a switching dc-dc converter is used to generate continuous envelope tracking control signal, then the efficiency is improved, but the bandwidth is limited due to the switching frequency requirements

Engineering Contradiction:

ImproveefficiencyVSAvoidbandwidth

Core Design Contradiction:

Loss of energyVSSpeed

Solution Approach 1:

The invention makes the switching frequency dynamic by allowing it to vary with the envelope signal amplitude. The switching frequency is highest when the envelope amplitude is largest and decreases when the amplitude is smaller, enabling the converter to track wide bandwidth envelope variations while maintaining high efficiency through resonant operation at each instantaneous frequency.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention uses periodic switching action with variable period duration. By adjusting the switching period dynamically based on the envelope signal characteristics, the converter achieves both high efficiency through periodic resonant operation and high bandwidth through adaptive frequency adjustment, eliminating the trade-off between efficiency and bandwidth.

Inventive Principle:

Principle #19Periodic action

3Speed

If GaN or GaAs transistors are used in the switching dc-dc converter to achieve fast switching, then the switching speed is improved, but the manufacturing cost is significantly increased

Engineering Contradiction:

Improveswitching speedVSAvoidmanufacturing cost

Core Design Contradiction:

SpeedVSEase of manufacture

Solution Approach 1:

The invention uses inexpensive silicon-based MOSFETs or IGBTs instead of expensive GaN or GaAs transistors. By operating the switching devices in discontinuous conduction mode with optimized switching waveforms and resonant circuits, the patent achieves fast effective switching performance with low-cost silicon devices, eliminating the need for expensive wide-bandgap semiconductor technologies.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention substitutes the need for ultra-fast switching hardware with a control strategy based on resonant circuits and capacitive coupling. Instead of relying on the inherent fast switching characteristics of expensive GaN/GaAs transistors, the patent uses LC resonant circuits to achieve fast voltage transitions and tracking, replacing the need for expensive high-speed switching devices with cheaper resonant-based speed enhancement.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10164575B2System for monitoring the peak power for an RF power amplification and associated method of calculating peak value and of selecting supply voltage

Publication Date: 2018.12.25 WUPATEC

AI summary

Disclosed is a system for monitoring the peak power of a telecommunication signal to be transmitted for RF power amplification of the telecommunication signal to be transmitted, including a digital processing device, a digital to RF converter and a dc-dc converter, wherein the output of the dc-dc converter can take a discrete voltage value from N discrete voltage values, N being an integer equal to or greater than 2, the digital processing device including a processing path including an envelope tracking control logic adapted to create a continuous envelope tracking control signal. The processing path further includes logic for driving the dc-dc converter including a peak value calculating device and a power supply voltage selecting device.