Stacked Peaker Load Modulation PA for Wide Back-Off Efficiency
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Solution Overview
Problem
Conventional quadrature combined load modulation power amplifiers face limitations in achieving high power-added efficiency and extended power backed off efficiency range due to constraints in breakdown voltage and increased peaker device periphery, which results in lower bandwidth and higher impedance transformation matching networks.
Innovation Solution
The use of stacked transistors in peaker amplifiers for quadrature combined load modulation power amplifiers allows for higher voltage and peak power operation, increasing off-state peaker output impedance to minimize loading effects on the carrier amplifier, thereby enhancing power backed off efficiency and range while preserving bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a larger peaker device periphery is used to extend the power backed off efficiency peak range beyond the traditional 6 dB PBO point, then the power backed off efficiency range is improved, but the bandwidth is reduced and the impedance transformation matching networks become more complex
Solution Approach 1:
The patent employs asymmetric supply operation where the peaker amplifier and carrier amplifier operate at different supply voltages. The peaker amplifier uses a higher supply voltage to enable extended power backed off efficiency operation, while the carrier amplifier operates at a lower supply voltage. This asymmetric voltage approach allows the peaker to maintain higher efficiency over a broader power range without requiring larger device periphery, thereby preserving bandwidth.
2Power
If asymmetric supply operation is used to improve the high efficiency power backed off range, then the power backed off efficiency is improved, but the maximum supply operation is constrained by the breakdown voltage of the technology
Solution Approach 1:
The patent segments the power amplification function into two separate amplifiers with different supply voltages: a peaker amplifier operating at a higher supply voltage for peak power efficiency, and a carrier amplifier operating at a lower supply voltage for continuous power operation. This segmentation allows each amplifier to be optimized for its specific operating regime without exceeding device breakdown voltage limits, thereby improving overall power backed off efficiency while maintaining reliability.
3Use of energy by moving object
If different voltage-efficient power devices are designed and monolithically integrated to improve asymmetric supply load modulation operation, then the voltage efficiency is improved, but the manufacturing complexity increases due to separate optimized epitaxial growth and additional reliability qualification
Solution Approach 1:
The patent uses a single semiconductor device technology platform that can support multiple supply voltage operations through circuit-level design rather than requiring separate optimized epitaxial growth for different voltage ratings. The same device structure is used in both peaker and carrier amplifiers, but they operate at different supply voltages achieved through circuit configuration. This universal approach reduces manufacturing complexity while maintaining voltage efficiency.
Data Source
AI summary
A load modulation amplifier is disclosed having a first power amplifier configured to amplify a first portion of a radio frequency signal below a threshold level. A second power amplifier has an N stack of transistor devices configured in a cascode configuration to amplify a second portion of the radio frequency signal that is above the threshold level, wherein N is a counting number that is greater than one.