Doherty Power Amplifier Combiner for 2nd Harmonic Injection
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Solution Overview
Problem
Power amplifiers, particularly Doherty Power Amplifiers (DPAs), face challenges in achieving high efficiency and linearity across various power levels and bandwidths, especially in millimeter wave 5G communications due to low gain and inefficient operation of peaking amplifiers.
Innovation Solution
The integration of a novel 2nd harmonic combiner network within the DPA, which includes a λ/4 transmission line and LC resonant circuit, allows for 2nd harmonic injection into the peaking amplifier, enhancing efficiency by maintaining fundamental frequency characteristics while providing additional power capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional DPA design is used, then circuit design is elegant and basic structure is simple, but efficiency at back-off power levels is low
Solution Approach 1:
The patent combines the 2nd harmonic combining function with the fundamental frequency combining function into a single integrated combiner network. The combiner network simultaneously combines fundamental frequencies from carrier and peaking amplifiers while also combining 2nd harmonics from peaking amplifiers and redirecting them to carrier amplifier outputs, eliminating the need for separate harmonic combining circuits and improving back-off efficiency without proportionally increasing complexity.
Solution Approach 2:
The combiner network is designed to perform multiple functions: combining fundamental frequencies from multiple amplifiers, combining 2nd harmonics from peaking amplifiers, and redirecting 2nd harmonics to carrier amplifier outputs. This multi-functional design allows a single circuit element to address multiple performance requirements simultaneously, improving overall efficiency while managing complexity.
2Power
If peaking amplifiers operate at low power levels, then power consumption is reduced, but efficiency and power capability are insufficient
Solution Approach 1:
The patent ensures continuous useful action by maintaining peaking amplifier efficiency across different power levels through 2nd harmonic combining. The harmonics from peaking amplifiers operating at low power levels are combined and redirected to carrier amplifier outputs, allowing peaking amplifiers to contribute useful power even when operating below full power, thereby maintaining overall system power capability and efficiency continuously across the operating range.
Solution Approach 2:
The patent converts the harmful effect of 2nd harmonics generated by peaking amplifiers operating at low power levels into a beneficial resource. Instead of treating these harmonics as unwanted byproducts that reduce efficiency, the combiner network captures and redirects them to carrier amplifier outputs, transforming them into useful power contribution and improving overall system efficiency and power capability.
3Speed
If DPA operates in millimeter wave spectrum, then 5G communication capabilities are enabled, but gain is low and linearity is difficult to maintain
Solution Approach 1:
The patent addresses linearity and gain stability challenges in millimeter wave operation by changing the operating parameters of the amplifier system through 2nd harmonic combining. By redirecting 2nd harmonics to carrier amplifier outputs, the system modifies the effective load seen by peaking amplifiers and improves overall linearity and gain stability across the millimeter wave frequency range, enabling reliable 5G communication performance.
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 solution achieves higher efficiency and linearity for DPAs in millimeter wave applications, addressing the limitations of traditional DPA designs by optimizing power amplification and reducing power consumption.
Implementation Method 1
LC resonant circuit
Implementation Method 2
λ/4 transmission line
Data Source
AI summary
Examples disclosed herein relate to a Doherty Power Amplifier (“DPA”) with integrated second harmonic injection. The DPA includes an amplifier circuit having a carrier amplifier and a peaking amplifier, and a combiner network coupled to the amplifier circuit, the combiner network having a plurality of transmission lines and a LC resonant circuit to inject a second harmonic from the carrier amplifier into the peaking amplifier.