RF Power Amplifier Compensation Using Digital Baseband Control

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Solution Overview

Problem

Conventional wireless RF modules face challenges in flexibly adjusting output signal characteristics of the power amplification unit due to factors like ambient temperature and memory effects, leading to discrepancies between actual and required output power characteristics, particularly in systems like GSM, where analog circuit adjustments are complex and inflexible.

Innovation Solution

A method involving a baseband unit connected to the power amplification unit through a control unit and RF transceiver, using digital-to-analog conversion to send control signals that regulate output signal characteristics, such as output power and spectrum, by establishing lookup tables or behavioral models to ensure compliance with system specifications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If analog circuit adjustment is used to control the power amplification unit, then the output power can be regulated, but the adjustment becomes complex and inflexible due to analog circuit complexity and process variation

Engineering Contradiction:

Improveflexibility of adjustmentVSAvoidcomplexity of analog circuit

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces the analog circuit adjustment mechanism with a digital control system. The baseband unit sends digital control signals to regulate the power amplification unit's output characteristics, substituting the mechanical/analog adjustment process with a digital signal processing approach. This eliminates the complexity and inflexibility of analog circuits while maintaining the ability to regulate output power and characteristics.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If analog circuit adjustment is used to compensate for temperature and memory effects, then output power regulation is possible, but the compensation accuracy is insufficient due to process variation and circuit complexity

Engineering Contradiction:

Improveaccuracy of output power characteristicVSAvoidcomplexity of compensation circuit

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent substitutes the analog compensation circuit with a digital control system that can precisely measure and compensate for temperature and memory effects. The baseband unit processes digital control signals to accurately regulate the power amplification unit's output characteristics, achieving higher compensation accuracy without the process variation problems inherent in analog circuits.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback mechanism where the baseband unit continuously monitors the output characteristics of the power amplification unit and adjusts the control signals accordingly. This closed-loop control enables precise compensation for temperature and memory effects by comparing actual output with desired output and making real-time corrections.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If conventional analog control is used, then the power amplification unit can be regulated, but the adaptability to different system specifications (GSM, spectrum requirements, ACLR, EVM) is limited

Engineering Contradiction:

Improveadaptability to system specificationsVSAvoidflexibility of control

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent replaces the inflexible analog control system with a digital control system that can easily adapt to different system specifications. The baseband unit processes digital control signals that can be programmatically adjusted to meet various requirements such as GSM standards, spectrum masks, ACLR, and EVM specifications, providing both adaptability and ease of operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for precise adjustment of output signal characteristics, including power-vs-time curves and ACLR, EVM, to meet specific system requirements, enhancing flexibility and accuracy in compensating for variations caused by temperature and other factors.

Implementation Method 1

enabling the baseband unit to converts the digital control signal into an analog control signal through a digital to analog converter (DAC)

Methodology Applied

Scientific EffectDigital-to-analog conversion:

Data Source

PatentUS9331645B2Method for compensating a power amplification unit of a wireless RF module

Publication Date: 2016.05.03 AIROHA TECHNOLOGY CORPORATION

AI summary

The present invention relates to a method for compensating a power amplification unit of a wireless RF module that includes a baseband unit, a RF transceiver unit, a power amplification unit and a control unit. The baseband unit is connected to the power amplification unit through the control unit and the RF transceiver unit. Based on the characteristic of the power amplification unit, the baseband unit provides a control signal to regulate the output signal characteristic of the power amplification unit, or provides a RF transceiver unit control signal to regulate the characteristics of the RF signal being transmitted by the RF transceiver unit to the power amplification unit, or to regulate the characteristics of the baseband signal being transmitted to the RF transceiver unit, enabling the characteristics of the output signal of the power amplification unit to meet the specifications of the related system.