Wideband Envelope Tracking Circuit for PA Linearity and CMOS Efficiency
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Solution Overview
Problem
Power amplifier systems in mobile devices face challenges in achieving high data rates and linearity, especially when using carrier aggregation, and manufacturing costs are increased by requiring semiconductor processing, which can result in poor linearity when using CMOS processing.
Innovation Solution
An envelope tracking system that includes a DC-to-DC converter, current digital-to-analog converters, error amplifiers, and AC combiners generates power amplifier supply voltages based on digital envelope signals, improving linearity and efficiency by dynamically adjusting voltage levels according to the RF signal envelope, allowing for the use of CMOS processing while maintaining high data rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If semiconductor processing is used to manufacture power amplifier systems, then manufacturing precision and ease of manufacture are improved, but linearity deteriorates when using CMOS processing
Solution Approach 1:
The system separates the power amplifier into two distinct paths: a high-linearity path using specialized processing for critical signal components, and a CMOS path for other functions. This segmentation allows each path to be optimized for its specific requirement, maintaining overall system linearity while enabling cost-effective CMOS manufacturing for non-critical components.
Solution Approach 2:
Different processing qualities are applied to different parts of the system. Critical components requiring high linearity receive specialized semiconductor processing, while non-critical components use standard CMOS processing. This local differentiation of quality enables cost reduction without sacrificing overall system performance.
2Use of energy by moving object
If envelope tracking is used to reduce power consumption, then energy efficiency is improved, but system complexity increases due to additional voltage control circuits
Solution Approach 1:
The envelope tracking voltage control circuit is merged with the existing power management infrastructure of the mobile device. The DC-to-DC converter and voltage control mechanisms are integrated into the device's standard power delivery network, allowing envelope tracking functionality to be added without proportionally increasing overall system complexity.
Solution Approach 2:
The power management circuits are designed to serve multiple functions: standard power delivery for normal operation and dynamic voltage adjustment for envelope tracking. This multi-functionality reduces the need for dedicated separate circuits, thereby limiting the increase in system complexity while maintaining power savings.
3Loss of energy
If dynamic voltage adjustment is implemented for envelope tracking, then power efficiency is improved, but voltage regulation precision becomes more difficult to maintain
Solution Approach 1:
A feedback control mechanism is implemented in the voltage regulation circuit to continuously monitor and adjust the supply voltage to the power amplifier. This feedback loop compensates for dynamic changes in voltage requirements during envelope tracking, maintaining precise voltage regulation despite the time-varying nature of the tracking signal.
Solution Approach 2:
The voltage regulation circuit is designed with preliminary compensation for expected voltage variations based on the envelope signal characteristics. By anticipating and pre-adjusting for voltage changes, the system maintains regulation precision without requiring excessively complex real-time control mechanisms.
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 envelope tracking system enhances power amplifier performance and linearity, reduces power consumption, and allows for cost-effective CMOS processing, enabling efficient operation across multiple frequency bands and carrier aggregation.
Implementation Method 1
generating a regulated voltage from a battery voltage using a DC-to-DC converter
Implementation Method 2
the first error amplifier electrically connected with negative feedback
Data Source
AI summary
Apparatus and methods for wideband envelope tracking systems are disclosed herein. In certain implementations, an envelope tracker includes a DC-to-DC converter, a current digital-to-analog converter (DAC), an error amplifier, a feedback circuit, and an AC combiner. The current DAC receives a digital envelope signal, and uses the digital envelope signal to generate an envelope current. The feedback circuit is connected between an output and an inverting input of the error amplifier, and the envelope current is provided to the error amplifier's inverting input. Additionally, the AC combiner generates a power amplifier supply voltage by combining an output of the DC-to-DC converter and an output of the error amplifier.