Power Amplifier Module Phase and Power Control for Stable Linearity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Doherty amplifiers require detailed bias level settings due to variations in transistor and matching circuit element characteristics, leading to inefficiencies and the need for predistortion systems to compensate for distortion.
Innovation Solution
A power amplifier module comprising a first amplifier, a power splitter, a second amplifier, a third amplifier, a phase shifter, a combining unit, and a controller, where the phase shifter and signal adjustment unit are used to control the power level and phase of the signals, reducing the influence of transistor characteristics and maintaining linear characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If detailed bias level settings are used to compensate for transistor and matching circuit variations, then amplifier efficiency is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the bias level parameter from detailed individual settings to a unified class-AB bias configuration. By setting both the carrier amplifier and peaking amplifier to operate in class-AB mode with a specific bias current range, the system achieves high efficiency without requiring complex individual bias adjustments for each transistor, thereby resolving the contradiction between efficiency and complexity
Solution Approach 2:
The patent enables the amplifier system to automatically adapt to transistor variations through the inherent characteristics of class-AB operation. The bias circuit provides a stable bias current that allows the amplifiers to self-adjust to component variations, eliminating the need for manual predistortion systems and complex bias level settings, thus reducing device complexity while maintaining efficiency
2Reliability
If predistortion systems are introduced to compensate for distortion characteristics, then linearity is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the need for separate predistortion systems by adopting class-AB operation for both amplifiers. This operational mode inherently provides better linearity compared to traditional class-C peaking amplifiers, allowing the system to achieve high signal quality without adding complex predistortion compensation circuits
Solution Approach 2:
Instead of using class-C bias for the peaking amplifier and adding predistortion to compensate for non-linearity, the patent inverts the approach by using class-AB bias from the start. This reversal of the biasing strategy provides inherent linearity, eliminating the need for additional predistortion systems and reducing overall device complexity
3Loss of energy
If class-C bias level is optimized for peaking amplifier operation timing, then amplifier efficiency is improved, but sensitivity to transistor variations increases
Solution Approach 1:
The patent changes the bias level parameter from class-C to class-AB for the peaking amplifier. This parameter change provides a more robust operating point that is less sensitive to transistor variations. The class-AB mode with a defined bias current range maintains高效率 operation while offering greater tolerance to component tolerances, thereby reducing the impact of manufacturing variations
Data Source
AI summary
A power amplifier module includes a first amplifier, a power splitter, a second amplifier, a third amplifier, a phase shifter, a combining unit, and a controller. The first amplifier amplifies a first signal and outputs a second signal. The power splitter splits the second signal into a third signal and a fourth signal. The second amplifier amplifies the third signal and outputs a fifth signal. The third amplifier amplifies the fourth signal and outputs a sixth signal. The phase shifter receives the fifth signal and shifts a phase of the fifth signal. The combining unit combines the fifth signal having the phase shifted by the phase shifter and the sixth signal and outputs an amplified signal of the second signal. The controller outputs a first control signal for controlling a power level of the sixth signal output from the third amplifier.