RF Power Amplifier Supply Modulation to Cut Switching Loss
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Solution Overview
Problem
Power amplifiers in wireless communication devices face a decline in power efficiency due to the power loss in switching amplifiers, particularly in low power modes, leading to a decrease in overall power efficiency.
Innovation Solution
A power amplifier design that divides the AM component into multiple control signals, each amplified by separate control signal amplifiers with pulse modulators, switching amplifiers, and low-pass filters, with the output of one low-pass filter used as a supply voltage for the RF amplifier and subsequent switching amplifiers, reducing dynamic range and switching loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single switching amplifier is used to amplify the AM component, then the device complexity is reduced, but the power efficiency decreases due to high switching loss in low power modes
Solution Approach 1:
The patent divides the single AM component signal into multiple control signals (first control signal and second control signal) with different dynamic ranges. Each control signal is amplified by a separate switching amplifier (first switching amplifier and second switching amplifier). This segmentation allows each amplifier to operate in an optimal efficiency range, reducing overall switching loss while distributing the amplification task across multiple devices.
Solution Approach 2:
The patent dynamically adjusts the supply voltage to each switching amplifier using low-pass filters that process the respective control signals. The first low-pass filter generates a first supply voltage for the first switching amplifier, and the second low-pass filter generates a second supply voltage for the second switching amplifier. This dynamic voltage adjustment optimizes the operating point of each amplifier according to the signal characteristics, improving power efficiency across different power modes.
2Loss of energy
If the AM component is amplified with high power, then the output power is increased, but the power efficiency decreases due to excessive switching loss
Solution Approach 1:
The patent segments the high-power AM component amplification task into two separate switching amplifiers. The first switching amplifier handles the first control signal with a larger dynamic range, while the second switching amplifier handles the second control signal with a smaller dynamic range. This segmentation allows each amplifier to operate more efficiently even at high output power levels, reducing the total switching loss compared to a single amplifier handling the full power range.
Solution Approach 2:
The patent changes the operating parameters of the switching amplifiers by providing different supply voltages through the low-pass filters. The first switching amplifier receives a first supply voltage and the second switching amplifier receives a second supply voltage, which are dynamically adjusted based on the control signals. This parameter adjustment optimizes the efficiency-power tradeoff, allowing high output power to be achieved while maintaining better power efficiency through reduced switching loss.
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 design enhances power efficiency by minimizing switching loss and maintaining high efficiency even in low power modes, improving the overall performance of the power amplifier.
Implementation Method 1
a pulse modulator modulating a pulse of the control signals
Implementation Method 2
a switching amplifier amplifying a current of a square wave signal from the pulse modulator
Implementation Method 3
a low-pass filter removing a spurious component caused by the square wave signal from an output signal of the switching amplifier
Implementation Method 4
an RF amplifier outputting the PM component by amplifying the PM component and performing amplitude modulation on the PM component using an output signal from the low-pass filter
Data Source
AI summary
A power amplifier is provided with a signal generating circuit, a plurality of control signal amplifiers and an RF amplifier. The signal generating circuit outputs the amplitude modulation components of an input signal by dividing the components into a plurality of control signals, and outputs a modulation wave signal or the phase modulation components of the modulation wave signal. The control signal amplifier is provided with a pulse modulator, which performs pulse modulation of a control signal; a switching amplifier, which performs current amplification of a rectangular wave signal outputted from the pulse modulator; and a low-pass filter, which removes spurious components from the signal outputted from the switching amplifier. The RF amplifier amplifies the inputted signal, performs amplitude modulation with the signal outputted from the low-pass filter and outputs the amplitude-modulated signal.