Envelope Tracking Power Supply Offset Capacitive Element
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Solution Overview
Problem
Switching power supplies in RF communication systems experience disruptions when transitioning from envelope tracking to average power tracking, affecting the envelope power supply signal and proper operation of RF PAs, especially at low output power levels.
Innovation Solution
An envelope tracking power supply with an offset capacitive element is introduced, allowing a transition through a intermediate mode to smooth the voltage change, reducing disruptions by coupling the offset capacitive element between the switching and analog outputs, and enabling a controlled voltage transition from envelope tracking to average power tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the envelope tracking power supply transitions directly from envelope tracking mode to average power tracking mode, then the transition is simple and fast, but a voltage dip occurs in the envelope power supply signal due to the offset capacitive element
Solution Approach 1:
The direct transition from envelope tracking mode to average power tracking mode is segmented into two separate transitions by introducing an intermediate mode. The first transition goes from envelope tracking mode to intermediate mode, and the second transition goes from intermediate mode to average power tracking mode. This segmentation allows the offset capacitive element to be properly managed during the transition, preventing voltage dips while maintaining reasonable transition time.
Solution Approach 2:
An intermediate mode is introduced as a mediator between envelope tracking mode and average power tracking mode. This intermediate mode serves as a transition state where the power supply can adjust the voltage across the offset capacitive element properly before entering average power tracking mode, thereby preventing the voltage dip that would occur with direct transition.
2Device complexity
If the voltage across the offset capacitive element is not properly adjusted during mode transition, then the transition is simple, but a voltage dip occurs in the envelope power supply signal
Solution Approach 1:
Before transitioning from envelope tracking mode to average power tracking mode, the system performs preliminary action by first transitioning to an intermediate mode. In this intermediate mode, the voltage across the offset capacitive element is properly adjusted in advance, ensuring that when the final transition to average power tracking mode occurs, no voltage dip will occur in the envelope power supply signal.
Solution Approach 2:
The intermediate mode acts as an intermediary state that facilitates proper voltage adjustment across the offset capacitive element. This mediator mode allows the system to prepare the capacitive element for the upcoming transition to average power tracking mode, preventing signal instability without requiring complex direct control mechanisms.
3Loss of energy
If envelope tracking is used at low output power levels, then efficiency is maximized, but the system complexity increases due to mode transition requirements
Solution Approach 1:
The power supply system dynamically adapts its operating mode based on the output power level and operational requirements. At low output power levels, the system can operate in envelope tracking mode for maximum efficiency, while automatically transitioning to average power tracking mode when appropriate. The intermediate mode provides a smooth dynamic transition between these states, managing complexity through adaptive behavior rather than fixed complex control logic.
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
This solution minimizes voltage dips during mode transitions, ensuring a stable envelope power supply signal and maintaining efficient operation of RF PAs across varying power levels by using a transition mode to adjust the voltage across the offset capacitive element.
Implementation Method 1
an offset capacitive element is coupled between a switching output and an analog output of the envelope tracking power supply
Data Source
AI summary
An envelope tracking power supply and an offset capacitive element are disclosed. The offset capacitive element is coupled between a switching output and an analog output of the envelope tracking power supply, which operates in one of an envelope tracking mode, a transition mode, and an average power tracking mode. During the envelope tracking mode, the envelope tracking power supply provides an envelope power supply signal using both the switching output and the analog output. During the transition mode, the envelope tracking power supply drives a voltage across the offset capacitive element from a first voltage to a second voltage, such that during a transition from the envelope tracking mode to the transition mode, the offset capacitive element has the first voltage, and during a transition from the transition mode to the average power tracking mode, the offset capacitive element has the second voltage.