Average Power Tracking Circuit for Fast RF Supply Voltage 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 increases battery current consumption, especially for user equipment operating at cell edges with poor signal-to-noise ratio.
Innovation Solution
Implementing an average power tracking (APT) system with a DC-to-DC converter and an error amplifier to rapidly transition the power amplifier supply voltage, using a control circuit and feedback mechanism to manage power levels based on the RF signal's average power, and incorporating a multi-level-supply DC-to-DC converter for efficient voltage regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional power amplifier supply system is used, then the system structure is simple, but the transient settling time is long and battery current consumption is high
Solution Approach 1:
The power management system is segmented into two distinct components: a DC-to-DC converter for efficient power conversion and an error amplifier for rapid transient response. This segmentation allows each component to specialize in its function, with the error amplifier providing fast settling time for supply voltage transitions while the DC-to-DC converter handles steady-state efficiency, thereby reducing overall transient settling time without excessive complexity
Solution Approach 2:
The error amplifier is configured to dynamically respond to transient conditions by detecting supply voltage deviations and rapidly adjusting its output to correct these deviations. This dynamic response mechanism enables the system to achieve fast transient settling time by actively compensating for voltage changes rather than relying on passive RC time constants
2Reliability
If the power amplifier supply voltage is increased to handle high PAPR signals, then linearity performance is improved, but battery current consumption increases
Solution Approach 1:
The error amplifier operates in a periodic feedback manner, continuously monitoring the supply voltage and making incremental adjustments as needed. This periodic action allows the system to maintain adequate supply voltage levels for linearity performance during high PAPR conditions while avoiding sustained high voltage operation that would increase battery current consumption, thereby achieving a balance between linearity and energy efficiency
Solution Approach 2:
The system dynamically changes the supply voltage parameter in response to transient conditions and average power levels. By adjusting the supply voltage only when and where needed rather than maintaining a constantly high voltage level, the system preserves linearity performance during critical moments while reducing battery current consumption during normal operation, thus resolving the contradiction between reliability and energy use
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
The APT system effectively manages power amplifier supply voltage transitions, reducing linearity constraints and battery current consumption, ensuring efficient operation even under high PAPR conditions.
Implementation Method 1
an error amplifier configured to operate in combination with one another to transition the power amplifier supply voltage from a first average power tracking voltage level to a second average power tracking voltage level
Implementation Method 2
The power management system includes a direct current (DC)-to-DC converter
Implementation Method 3
a feedback circuit electrically connected between the power amplifier supply voltage and a second input of the error amplifier
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.