RF Power Amplifier Load Modulation for High-PAPR Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power amplifiers in communication systems, such as those used for LTE and DTV transmissions, suffer from low efficiency due to high peak-to-average power ratios, leading to high power consumption in both mobile devices and base stations.
Innovation Solution
The implementation of an amplifier circuit that combines dynamic load modulation and supply modulation, using a charge pump modulator and a tuneable matching network, to optimize the supply voltage and load impedance based on the output power range, thereby enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional power amplifiers are used to handle high peak-to-average power ratio signals, then the communication signals can be transmitted, but the power amplifier efficiency becomes very low
Solution Approach 1:
The patent implements dynamic supply voltage modulation and dynamic load impedance modulation to adapt the power amplifier's operating conditions to the instantaneous signal requirements. The supply voltage is dynamically adjusted based on the envelope of the modulated signal, and the load impedance is dynamically tuned using a varactor-diode-based matching network, enabling the amplifier to operate efficiently across varying power levels and resolve the contradiction between handling high PAPR signals and maintaining efficiency.
Solution Approach 2:
The patent changes key operating parameters of the power amplifier dynamically: the supply voltage parameter is modulated in accordance with the signal envelope, and the load impedance parameter is adjusted through variable capacitance elements in the matching network. These parameter changes allow the amplifier to maintain optimal efficiency across different operating conditions while handling high peak-to-average power ratio signals.
2Power
If the supply voltage is increased to improve output power capability, then higher output power can be achieved, but the power consumption increases
Solution Approach 1:
The supply voltage to the power amplifier is dynamically modulated according to the envelope of the modulated signal rather than being held at a constant high level. This dynamic adjustment allows the amplifier to deliver high output power when needed while consuming less power during lower signal levels, resolving the contradiction between output power capability and power consumption.
Solution Approach 2:
The patent maintains continuous efficient operation by ensuring the supply voltage and load impedance are continuously adjusted to match the instantaneous requirements of the signal being amplified. This continuous adaptation prevents energy waste and maintains high efficiency across the full dynamic range of output power levels.
Data Source
AI summary
In one embodiment an amplifier circuit is disclosed. The amplifier circuit comprises an amplifying device configured to amplify a radiofrequency signal, the amplifying device having an output dynamic range; a supply modulator configured to modulate a supply voltage supplied to the amplifying device when an output of the amplifying device is within a first region of the output dynamic range; a tuneable matching network coupled to an output of the amplifying device; and a load controller configured to control the tuneable matching network, when the output of the amplifying device is within a second region of the output dynamic range, and thereby modulate the load to which the output of the amplifying device is applied.