Multiple Output Charge Pump with Frequency-Limited Envelope Tracking
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Solution Overview
Problem
Conventional DC-DC power converters in envelope-tracking power amplifiers experience excessive switching losses at high frequencies, leading to increased power consumption and overheating, which is costly to mitigate with advanced transistor devices and complex inductor-based designs.
Innovation Solution
Implementing a frequency-limited envelope tracking power converter with a multiple-output charge pump and a peak following frequency divider circuit to dynamically adjust the supply voltage, limiting switching frequency and using conventional transistor architectures, thereby reducing switching losses and avoiding overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the switching frequency of the DC-DC power converter is increased to match the signal transmission frequency for envelope tracking, then the power amplifier can dynamically adjust supply voltage to track RF envelope, but the transistor switching losses increase excessively leading to power consumption and overheating
Solution Approach 1:
The patent divides the envelope tracking operation into multiple discrete voltage levels (e.g., 8 levels from 2.5V to 7.5V) instead of continuous adjustment. The controller selects appropriate voltage levels based on the instantaneous power requirements, reducing the switching frequency and thus transistor switching losses while maintaining envelope tracking functionality.
Solution Approach 2:
The patent implements partial envelope tracking by providing a subset of possible voltage levels rather than the full continuous range. This partial action approach reduces the switching frequency and transistor losses while still achieving sufficient power amplification for the transmitted signal, accepting some loss in tracking precision to gain efficiency.
2Loss of energy
If advanced specialized transistor devices are used to reduce switching losses, then power consumption and overheating are mitigated, but the cost of the power converter increases
Solution Approach 1:
The patent changes the operating parameters of conventional transistors by limiting their switching frequency through multi-level voltage selection rather than high-frequency continuous switching. This parameter change allows the use of standard, cost-effective transistor devices while achieving reduced switching losses through lower switching frequency and partial-step voltage transitions.
3Productivity
If inductors are used in the DC-DC power converter to achieve envelope tracking, then the power amplifier can be supplied with dynamic voltage, but the manufacture and implementation in system-on-chip becomes complicated
Solution Approach 1:
The patent replaces the mechanical/physical inductor-based DC-DC converter with an electronic switched-capacitor charge pump circuit. This substitution eliminates the need for bulky inductors and complex magnetic components, enabling integration into system-on-chip architectures while still providing dynamic voltage supply capability through capacitive energy storage and transfer.
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 approach reduces power consumption and heat generation while allowing the use of conventional transistors, enhancing efficiency and cost-effectiveness by limiting switching frequency and employing partial-step envelope tracking.
Implementation Method 1
a first capacitor pump stage, a second capacitor pump stage, and a third capacitor pump stage
Data Source
AI summary
A power converter for a load with varying power requirements dynamically adjusts its supply voltage to the load so as to track the radio frequency (RF) envelope of the signal being carried by the load. The supply voltage can be provided by a multiple-output charge pump providing multiple output voltage levels concurrently, and a switch to provide a selected one of the different output voltage levels as the supply voltage to the load. A controller controls the switch to dynamically modify the voltage level selected for output as the supply voltage such that the supply voltage tracks the RF envelope of the signal being carried by the load. As the switching losses of transistors of the power converter may exceed the power savings achieved through envelope tracking, the power converter employs a peak following frequency divider circuit that limits the switching frequency of the power converter to a threshold frequency.