RF Power Amplifier Supply with Split Envelope and Constant On-Time Control
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Solution Overview
Problem
Existing hybrid power supplies for radio-frequency power amplifiers face efficiency reduction due to increased envelope signal bandwidth, high peak-to-average power ratio, and sensitivity to output noise, leading to increased power losses and instability.
Innovation Solution
A power supply system comprising a first linear circuit for low-power signal amplification, a second linear circuit for high-power signal amplification, and a third circuit for constant on-time or constant off-time control, which classifies and manages power ratios to provide adaptive energy efficiently, reducing power losses and noise sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hysteresis control technology is used to combine linear amplification with switching power supply, then system stability is improved, but switching frequency increases with envelope signal bandwidth, challenging on/off control
Solution Approach 1:
The patent segments the power supply into three distinct circuits: a first linear circuit for low-power signals (≤30%), a second linear circuit for high-power signals (≥70%), and a third switching circuit. This segmentation allows each circuit to operate in its optimal regime, preventing the switching frequency from increasing with bandwidth while maintaining stability.
Solution Approach 2:
The patent changes the operating parameters by using constant on-time or constant off-time control in the third circuit instead of traditional hysteresis control. This parameter change decouples the switching frequency from the envelope signal bandwidth, allowing the system to maintain stable operation without excessive switching frequency increases.
2Reliability
If hysteresis control technology is used, then linear amplification is combined with switching power supply, but on-time point is highly sensitive to output noise, causing on-time to lag behind optimal on/off time point
Solution Approach 1:
The patent applies preliminary action by using constant on-time or constant off-time control that proactively determines the optimal switching moments before noise can affect the decision. This eliminates the lag between the actual optimal on/off time and the triggered on-time, as the switching timing is predetermined rather than reactively determined by noisy feedback.
3Productivity
If hysteresis control technology is used to process envelope signal with wide bandwidth and high PAPR, then power amplification is achieved, but output power losses of switching power supply and linear-amplification-related circuit increase simultaneously, reducing overall system efficiency
Solution Approach 1:
The patent applies local quality by assigning different operational characteristics to different parts of the power supply. The first and second linear circuits handle low-power and high-power signals with high efficiency, while the third switching circuit handles intermediate power levels. This localized optimization ensures that each circuit operates in its most efficient regime, minimizing overall power losses while maintaining the ability to handle wide bandwidth and high PAPR signals.
Data Source
AI summary
A power supply for a radio-frequency power amplifier includes: first and second linear circuits, configured to linearly amplify a low-power signal and a high-power signal in a first envelope signal respectively and provide first and second voltages to the radio-frequency power amplifier respectively, wherein the low-power signal is a signal with a power ratio less than or equal to 30% in the envelope signal, and the high-power signal other than the low-power signal is a signal with a power ratio greater than or equal to 70% in the envelope signal; and a third circuit, configured to detect the linearly-amplified high-power signal and work in a constant on time control mode having a constant on time or a constant off time control mode having a constant off time so as to provide a third electric current to the radio-frequency power amplifier according to the detected linearly-amplified high-power signal.