RF Power Amplifier Duty Cycle Modulation for Efficient Power Back-Off
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Solution Overview
Problem
Nonlinear class RF power amplifiers have a narrow dynamic range in terms of linearity and efficiency, leading to degraded power efficiency when operating at output powers lower than their maximum supported power.
Innovation Solution
A duty cycle controller adjusts the duty cycle of a frequency-modulated (FM) signal based on a target output power, reducing the duty cycle to lower the power consumption and output power of the power amplifier while maintaining high power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If nonlinear class power amplifiers are used to achieve better power efficiency, then power efficiency is improved, but the dynamic range in terms of linearity and efficiency becomes narrow
Solution Approach 1:
The system dynamically adjusts the duty cycle of the RF signal based on the desired output power level. By varying the duty cycle rather than using a fixed operating point, the power amplifier can maintain high efficiency across a wide dynamic range, adapting to different power requirements while preserving the benefits of nonlinear class operation
Solution Approach 2:
The invention changes the duty cycle parameter of the RF signal to control output power while maintaining efficiency. This parameter adjustment allows the system to operate the nonlinear power amplifier at different duty cycles, effectively expanding the dynamic range without sacrificing the inherent power efficiency of nonlinear class amplifiers
2Power
If nonlinear class power amplifiers operate at lower output power, then output power is reduced, but power efficiency degrades
Solution Approach 1:
The system uses periodic duty cycle adjustment where the RF signal is transmitted in pulses with variable duty cycles. This periodic action allows the power amplifier to operate at full efficiency during active periods while reducing average power consumption by controlling the proportion of time the amplifier is active, thereby maintaining high efficiency at lower output power levels
Data Source
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AI summary
This disclosure provides methods, devices, and systems for wireless communications. The present implementations more specifically relate to reducing the power consumption of radio frequency (RF) power amplifiers without sacrificing power efficiency. In some aspects, an RF transmitter may include a modulator, a power amplifier, and a duty cycle controller coupled between the modulator and the power amplifier. The modulator is configured to modulate data onto a carrier signal according to a frequency modulation (FM) scheme. The duty cycle controller is configured to adjust a duty cycle of the FM signal based on a target output power associated with the power amplifier. In some implementations, the duty cycle controller may reduce the duty cycle of the FM signal so that the adjusted duty cycle causes the power amplifier to operate at the target output power. The power amplifier amplifies the adjusted FM signal for transmission over a wireless communication channel.