Doherty Amplifier Dynamic Phase Control for Efficiency
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Solution Overview
Problem
Doherty amplifiers face issues with unnecessary power consumption during back-off operations and power efficiency deterioration when the frequency of the signal to be amplified changes, due to the peak amplifier operating even when not needed and impedance mismatch between the carrier and peak amplifiers.
Innovation Solution
A Doherty amplifier design where the signal distributor adjusts the phase shift based on the signal's power and frequency, only outputting the second signal to the peak amplifier when its power is greater than or equal to a threshold, and adjusting the phase shifter's capacitance values to maintain a 90-degree phase shift, thereby preventing unnecessary power consumption and impedance mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the peak amplifier operates continuously to maintain high power efficiency, then power efficiency is improved, but unnecessary power consumption occurs during back-off operation
Solution Approach 1:
The patent applies dynamics by making the peak amplifier's operation state variable rather than fixed. The signal distributor dynamically controls whether to output signals to the peak amplifier based on real-time signal power levels. When the carrier amplifier operates in saturation region, the peak amplifier is activated; when operating in back-off region, the peak amplifier is deactivated. This dynamic operation mode resolves the contradiction between maintaining high power efficiency and avoiding unnecessary power consumption.
2Manufacturing precision
If the first transmission line and second transmission line are used to match impedance between carrier amplifier and peak amplifier, then impedance matching is improved, but power efficiency deteriorates when signal frequency changes
Solution Approach 1:
The patent applies dynamics by replacing fixed transmission lines with variable phase shifters that can adjust their phase shift characteristics according to signal frequency. The variable phase shifters maintain the 90-degree phase difference between carrier and peak amplifier paths across different frequencies, ensuring continuous impedance matching. This dynamic adjustment capability resolves the contradiction between achieving precise impedance matching and maintaining power efficiency across frequency variations.
3Device complexity
If the signal distributor always outputs signals to both carrier amplifier and peak amplifier, then the system structure is simplified, but unnecessary power consumption occurs
Solution Approach 1:
The patent applies preliminary action by having the signal distributor make advance decisions about signal routing based on detected signal power levels. Before signals are amplified, the distributor determines whether the peak amplifier needs to be activated. This preliminary control prevents unnecessary power consumption by ensuring the peak amplifier only operates when the carrier amplifier is in saturation region, resolving the contradiction between structural simplicity and energy efficiency.
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 effectively suppresses unnecessary power consumption and maintains high power efficiency even when the signal's frequency changes, by ensuring the peak amplifier only operates in the saturation region of the carrier amplifier and adjusting impedance to match changing frequencies.
Implementation Method 1
a phase shifter for delaying the phase of the other signal distributed by the distributor by 90 degrees
Implementation Method 2
adjusting the phase shifter's capacitance values to maintain a 90-degree phase shift
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
In a case where the power of a signal to be amplified is greater than or equal to a threshold value, a signal distributor (2) outputs one of signals to a carrier amplifier (6), outputs another signal, a phase of which is 90 degrees behind that of the one of the signals, to a peak amplifier (8), and adjusts a phase shift amount of a signal shifted by a phase shifter (7) depending on the frequency of the signal to be amplified. In a case where the power of the signal to be amplified is less than the threshold value, the signal distributor (2) outputs the one of the signals to the carrier amplifier (6) without outputting the other signal to the peak amplifier (8).