Mobile RF Envelope Tracking with Buck-Controlled PA Supply
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Solution Overview
Problem
There is a need for improved power amplifier systems and envelope trackers in mobile devices to efficiently manage RF signal amplification, reduce power consumption, and prevent signal interference, particularly in managing the power level of RF signals over time in mobile environments.
Innovation Solution
The proposed solution involves a mobile device configuration that includes a power amplifier, a buck converter, and an error amplifier. The buck converter converts battery voltage into a buck voltage, and the error amplifier generates an output current based on the RF signal envelope to adjust the power amplifier supply voltage, controlling the buck converter by changing the error current in relation to the output current. This configuration includes a buck controller, buck inductor, and buck switches, as well as an AC coupling capacitor between the power amplifier supply voltage and the error amplifier output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power amplifier supply voltage is increased to amplify RF signals, then the signal transmission capability is improved, but the power consumption increases
Solution Approach 1:
The patent implements dynamic supply voltage adjustment by tracking the envelope of the RF signal. The power amplifier supply voltage is dynamically modified to match the signal envelope characteristics, allowing the system to use higher voltage only when needed for signal transmission and reduce voltage during low-signal periods, thus resolving the contradiction between transmission capability and power consumption
Solution Approach 2:
The system changes the supply voltage parameter in real-time based on the RF signal envelope detection. By continuously adjusting the voltage parameter according to signal conditions, the system optimizes the balance between transmission performance and energy efficiency, addressing the technical contradiction
2Use of energy by moving object
If the power amplifier supply voltage is dynamically adjusted to reduce power consumption, then energy efficiency is improved, but the system complexity increases
Solution Approach 1:
The system segments the power control function into distinct components: an envelope detector that extracts signal amplitude information, a control circuit that processes this information, and a voltage regulation stage that adjusts the supply voltage. This segmentation allows each component to perform its function independently, managing overall system complexity while achieving dynamic power adjustment
Solution Approach 2:
The patent introduces an intermediary envelope detection and control circuit between the RF signal source and the power amplifier. This intermediary system translates complex RF signal characteristics into simple control voltages that regulate the power amplifier, reducing the complexity burden on the main power amplification path
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 enhances power efficiency by dynamically adjusting the power amplifier supply voltage based on the RF signal envelope, reducing power consumption and improving battery life while maintaining signal quality.
Implementation Method 1
The buck converter is configured to convert a battery voltage into a buck voltage, and to control a magnitude of the buck voltage based on an error current. The buck converter includes a buck controller, a buck inductor and a plurality of buck switches, and the buck controller is configured to use the error current to control a state of the plurality of buck switches so as to control a current through the buck inductor.
Implementation Method 2
an AC coupling capacitor electrically connected between the power amplifier supply voltage and an output of the error amplifier
Data Source
AI summary
Apparatus and methods for envelope tracking in a mobile device are disclosed herein. In certain configurations, a method includes amplifying a radio frequency (RF) input signal using a power amplifier, providing power to the power amplifier from a power amplifier supply voltage, controlling a voltage level of the power amplifier supply voltage based on a control voltage using a DC-to-DC converter, adjusting the voltage level of the power amplifier supply voltage based on an envelope of the RF input signal using an error amplifier, low pass filtering the power amplifier supply voltage to generate a filtered voltage using a low pass filter, and generating the control voltage based on comparing the filtered voltage to a reference voltage using a comparator.