Power Amplifier Supply Switching for Low-Power Efficiency
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Solution Overview
Problem
Conventional wireless transmitters with internal power amplifiers face inefficiency issues when operating at moderate or low power levels, as they are designed to run from the maximum battery supply, leading to low efficiency due to the characteristics of class AB amplifiers.
Innovation Solution
Implementing a power supply switching system that allows the power amplifier and its driver amplifier to operate from a lower supply voltage at moderate and low power levels, while maintaining high efficiency by using supply switches that tolerate high current and exhibit low series resistance, and ensuring the bias circuitry runs from the highest supply to maintain linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power amplifier runs from maximum battery supply to ensure full power capability, then the transmitter can operate at full power, but power efficiency deteriorates at moderate or low power levels
Solution Approach 1:
The patent implements dynamic supply voltage switching that adapts the power amplifier's supply voltage based on the required output power level. The system switches between a first supply voltage (higher) for full power operation and a second supply voltage (lower) for moderate or low power operation, making the system's operating parameters dynamic rather than fixed. This resolves the contradiction by allowing the amplifier to operate efficiently at both high and low power levels.
Solution Approach 2:
The patent changes the supply voltage parameter of the power amplifier based on operating conditions. By switching the supply voltage from a first value to a second value depending on the required power output, the system optimizes efficiency across different power levels. This parameter change approach allows the amplifier to maintain optimal efficiency whether operating at full power or reduced power levels.
2Loss of energy
If supply switching is implemented to improve efficiency at low power levels, then power efficiency improves, but device complexity increases due to additional switching circuitry
Solution Approach 1:
The power amplifier is designed to universally operate from multiple supply voltages without requiring separate amplifier circuits for different power levels. The single amplifier can efficiently operate from either the first or second supply voltage depending on the operating mode, eliminating the need for multiple dedicated amplifiers and reducing overall system complexity despite the added switching control.
Data Source
AI summary
To improve upon efficiency of a transmitter's power amplifier during low power operation, a switching system is used to selectively switch between different (e.g., normal and reduced) power supplies. Suitable hardware/software in the form of circuitry, logic gates, and/or code functions to process, amplify, and transmit an input RF signal and selectively switch IN/OUT a plurality of supply voltages using control logic.