Doherty Amplifier Drain Voltage Switching for Low-Power Efficiency
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Solution Overview
Problem
Conventional power amplification devices with Doherty amplifiers suffer from reduced power efficiency at lower input signal levels, which is a significant issue in mobile communication systems that operate over a wide output power range.
Innovation Solution
A power amplification device that includes a DC power supply, a Doherty amplifier with a voltage control circuit and a voltage converter circuit, which adjusts the drain voltage based on output power levels, applying lower voltage during low output power and higher voltage during high output power to improve efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a Doherty amplifier with fixed drain voltage is used to ensure high power output, then the saturated electric power is improved, but the power efficiency at low output power deteriorates
Solution Approach 1:
The patent applies dynamic voltage adjustment by switching between a first drain voltage (higher) and a second drain voltage (lower) based on the output power level. When the output power is below a threshold, the lower voltage is applied to improve efficiency; when above the threshold, the higher voltage is applied to ensure sufficient power output. This dynamic adaptation resolves the contradiction between maintaining high power capability and achieving low power consumption at partial load.
Solution Approach 2:
The invention changes the operating parameter (drain voltage) of the power amplifier based on the output power level. By controlling the voltage control circuit to switch between different voltage levels, the system optimizes the trade-off between power output and energy efficiency, directly addressing the contradiction between saturated power and low-power efficiency.
2Reliability
If a Doherty amplifier operates at high drain voltage to maintain performance across wide output power range, then the saturated power is ensured, but energy consumption increases at low signal levels
Solution Approach 1:
The system dynamically adjusts the drain voltage based on the current operating point and output power level. The voltage control circuit monitors the output power and switches between voltage levels accordingly, ensuring that the amplifier operates at optimal efficiency points while maintaining the ability to deliver high power when needed, thus reducing energy waste during low-signal operation.
Solution Approach 2:
The voltage switching operation occurs periodically or continuously based on the signal conditions, with the voltage control circuit monitoring output power levels and adjusting the drain voltage in real-time. This periodic adaptation allows the system to maintain performance reliability while minimizing energy consumption during low-signal periods.
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 enhances power efficiency by operating at lower voltages during low signal conditions and higher voltages during high signal conditions, thereby improving overall power amplification efficiency across the entire output power range.
Implementation Method 1
a voltage converter circuit that applies a second drain voltage obtained by subjecting the first drain voltage to voltage conversion
Data Source
Figure 1
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AI summary
Provided is a power amplification device including: a DC power supply that outputs a drain voltage; a Doherty amplifier including a carrier amplifier and a peak amplifier, which are connected in parallel, and amplifies an RF signal; a voltage control circuit that outputs a first instruction to output a low voltage when an output power is equal to or lower than a given value, and outputs a second instruction to output a high voltage when the output power is larger than the given value; and a voltage converter circuit that converts the drain voltage to a voltage lower than the drain voltage and applies the converted voltage to drain terminals of the carrier amplifier and the peak amplifier according to the first instruction, and applies the drain voltage directly to the drain terminals of the carrier amplifier and the peak amplifier according to the second instruction.