APT Power Amplifier Supply Control for Fast Transient Settling
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Solution Overview
Problem
The challenge in 5G NR communication systems is the high peak-to-average power ratio (PAPR) of RF signals, which poses linearity constraints for power amplifiers and can constrain output power and increase battery current, especially for user equipment operating at cell edges with poor signal-to-noise ratio.
Innovation Solution
Implementing an average power tracking (APT) system with fast transient settling, utilizing a power management system that includes a DC-to-DC converter and an error amplifier to transition the power amplifier supply voltage from one average power tracking level to another, controlled by a feedback circuit and a control circuit that senses output power and adjusts voltage levels accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power amplifier operates at high output power to maintain signal quality in poor signal-to-noise ratio conditions, then signal transmission quality is improved, but power consumption increases and battery current increases
Solution Approach 1:
The power amplifier supply voltage is dynamically adjusted to track the average output power of the power amplifier. The voltage transitions from a first average power tracking level to a second average power tracking level based on the actual power requirements, allowing the system to optimize power consumption while maintaining signal quality when needed
Solution Approach 2:
A feedback circuit is employed to sense the output power of the power amplifier and provide this information to the error amplifier. This closed-loop feedback mechanism enables the system to automatically adjust the supply voltage to match the actual power requirements, preventing unnecessary power consumption while maintaining signal transmission quality
2Speed
If the power amplifier supply voltage transitions quickly between different power levels, then transient response speed is improved, but transient impairments increase
Solution Approach 1:
The error amplifier begins adjusting the supply voltage in advance of the full power transition requirement. By starting the voltage transition early and continuously tracking the average power, the system prepares for power level changes smoothly, reducing the impact of transient impairments while maintaining fast overall response
Solution Approach 2:
The supply voltage transition is made dynamic and continuous rather than abrupt. The error amplifier continuously adjusts the voltage to track the average output power, creating a smooth transition that reduces transient disturbances while maintaining fast response capability
3Reliability
If the power amplifier supply voltage is maintained at a high level to ensure linearity, then linearity performance is improved, but power consumption increases
Solution Approach 1:
The supply voltage is dynamically adjusted to match the actual average output power requirements. When the power amplifier operates at lower power levels, the supply voltage is reduced accordingly, maintaining sufficient linearity for the current operating point while reducing power consumption compared to maintaining a constantly high voltage level
Solution Approach 2:
The supply voltage parameter is changed to track the average output power. By adjusting this critical parameter dynamically rather than maintaining it at a fixed high level, the system maintains adequate linearity performance for each operating condition while optimizing power consumption
Data Source
AI summary
Average power tracking (APT) systems with fast transient settling are disclosed. In certain embodiments, an APT system is used to provide a power amplifier supply voltage to a power amplifier that amplifies a radio frequency (RF) signal. The APT system controls the power amplifier supply voltage to track an average power of the RF signal, and includes a DC-to-DC converter that is assisted by an error amplifier in transitioning from one power amplifier supply voltage level to another power amplifier supply voltage level. Thus, the combination of a DC-to-DC converter with a fast changing error amplifier can swing enough AC voltage with a low enough slew rate to be able to rapidly transition the power amplifier supply voltage from one APT voltage level to another APT voltage level.