Parallel Doherty Amplifier Layout for Loop Oscillation Suppression
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Solution Overview
Problem
Doherty amplifiers connected in parallel can experience loop oscillation, which affects their operation and efficiency in amplifying high-frequency signals, especially when multiple amplifiers are connected, leading to potential instability and reduced performance.
Innovation Solution
Incorporating loop oscillation suppressors, such as resistors, between neighboring carrier and peak amplifiers, and ensuring that amplifiers of the same type are adjacent to each other, to prevent the conditions for loop oscillation from being met, thereby suppressing oscillation and enhancing stability across a broad frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple Doherty amplifiers are connected in parallel to amplify high-frequency signals, then the amplification capacity and efficiency are improved, but loop oscillation occurs between the amplifiers causing instability and reduced performance
Solution Approach 1:
A resistor is introduced as an intermediary component connected between neighboring carrier amplifiers and between neighboring peak amplifiers. This resistor acts as a mediator that suppresses loop oscillation by providing a controlled impedance path, preventing the harmful oscillatory feedback while allowing the parallel amplifier configuration to maintain its high amplification capacity.
Solution Approach 2:
The resistor, which inherently introduces some signal loss, is strategically placed to convert the potential harm of loop oscillation into a beneficial damping effect. By allowing controlled energy dissipation through the resistor, the harmful oscillations are suppressed, and the overall system stability is improved, making the amplifier configuration more reliable.
2Use of energy by moving object
If Doherty amplifiers are connected in parallel, then signal amplification efficiency is improved, but parasitic inductance and frequency-dependent issues arise causing loop oscillation
Solution Approach 1:
The resistor serves as an intermediary that counteracts the harmful effects of parasitic inductance in the parallel amplifier configuration. By providing a resistive damping path, it neutralizes the frequency-dependent oscillatory behavior caused by parasitic inductance, allowing the system to maintain high amplification efficiency across a broad frequency range.
Solution Approach 2:
The introduction of resistance changes the impedance parameters of the amplifier network. This parameter change transforms the system from one dominated by inductive reactance (which causes oscillation) to one with adequate damping, suppressing loop oscillation while preserving the efficient amplification characteristics of the parallel Doherty configuration.
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
The solution effectively suppresses loop oscillation between Doherty amplifiers, ensuring stable and efficient high-frequency signal amplification by preventing parasitic inductance and frequency-dependent issues, allowing for reliable operation even when multiple amplifiers are connected in parallel.
Implementation Method 1
a first loop oscillation suppressor locates between the second carrier amplifier and an associated first carrier amplifier or the second peak amplifier and the associated first peak amplifier
Data Source
Figure 1~2
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Figure 4
AI summary
A high frequency signal amplifying circuitry of an embodiment includes a first splitter (102), a first amplifier (1A), a second amplifier (1B), a loop oscillation suppressor (Rc-1), and a combiner (104). The first amplifier (1A) includes a second splitter (14A), a first carrier amplifier (20A), a first peak amplifier (18A), and a first combiner (24A). The second amplifier (1B) includes a third splitter (14B), a second carrier amplifier (20B), a second peak amplifier (18B), and a second combiner (24B). The second carrier amplifier (20B) being adjacent to an associated the first carrier amplifier (20A). The loop oscillation suppressor (Rc-1) located between the second carrier amplifier (20B) and the associated first carrier amplifier (20A).