Supply Modulator With Tunable Low Pass Filter for RF Power Efficiency
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Solution Overview
Problem
High Peak-to-Average Power Ratio (PAPR) in radio frequency power amplifiers for mobile communication devices leads to decreased power efficiency, particularly in the back-off power region, and existing methods like Average Power Tracking do not effectively track the envelope of the input signal in real time, resulting in power loss.
Innovation Solution
A supply modulator with a switched-mode power supplier and a tunable low pass filter, including multiple stages with variable impedances, that modulates the supply voltage based on the envelope signal to improve power efficiency and cover various frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a radio frequency power amplifier uses a direct current (DC) source, then the amplifier can operate stably, but the power efficiency decreases as the Peak-to-Average Power Ratio (PAPR) increases
Solution Approach 1:
The patent applies dynamics by transitioning from a static DC power supply to a dynamic envelope tracking power supply that adjusts the supply voltage in real-time according to the signal envelope, enabling the power amplifier to maintain high efficiency across varying power levels while preserving operational stability
Solution Approach 2:
The patent changes the supply voltage parameter dynamically by tracking the envelope signal and adjusting the power supply voltage accordingly, allowing the amplifier to operate at optimal efficiency points across different power levels rather than being constrained by a fixed DC voltage
2Use of energy by moving object
If an Average Power Tracking (APT) method is used to improve power efficiency in the back-off power region, then the average power efficiency improves, but the envelope of the input signal is not tracked in real time resulting in power loss
Solution Approach 1:
The patent implements feedback by continuously monitoring the envelope signal and using this information to adjust the power supply voltage in real-time, creating a closed-loop system that maintains optimal efficiency by responding dynamically to signal variations rather than relying on average power measurements
Solution Approach 2:
The patent applies preliminary action by pre-tracking the envelope signal before amplification and using this tracked information to prepare the appropriate supply voltage level in advance, ensuring the power amplifier operates at optimal efficiency points without real-time delay
3Use of energy by moving object
If an envelope tracking method is used to track the envelope of an input signal in real time, then the power efficiency improves, but the supply modulator requires high power efficiency and wide frequency bandwidth which increases device complexity
Solution Approach 1:
The patent applies universality by designing a supply modulator that can handle multiple frequency bands and envelope signal characteristics through a unified architecture, reducing the need for separate dedicated circuits for different frequency ranges while maintaining high efficiency and wide bandwidth coverage
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 solution enhances power efficiency by real-time tracking of the envelope signal, reducing power loss and improving the ability to handle signals across different frequency bands, thereby extending battery life in mobile communication devices.
Implementation Method 1
a low pass filter configured to generate the modulated voltage by filtering certain frequency band of the pulse signal
Implementation Method 2
each of the plurality of stages of the low pass filter includes at least one variable impedances
Data Source
AI summary
A transmitting device including: a modem configured to generate a baseband signal and an envelope data corresponding to the baseband signal; a supply modulator including a first switched-mode power supplier and a second switched-mode power supplier, the supply modulator configured to provide a modulated voltage to an output node based on the envelope data; and a power amplifier configured to amplify a carrier wave signal by using the modulated voltages, the carrier wave signal being associated with the baseband signal, wherein the first switched-mode power supplier includes: a pulse input node to receive a pulse signal generated in association with the envelope data; and a plurality of stages sequentially connected between the pulse input node and the output node, the plurality of stages configured to adjust the modulated voltage by filtering certain frequency band of the pulse signal, and the plurality of stages includes at least one variable impedance.