Segmented Power Amplifier Biasing for Linearity and Efficiency
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Solution Overview
Problem
Power amplifiers in RF systems face challenges in achieving both linearity and efficiency, with conventional adaptive/linearization biasing techniques being sensitive to process, voltage, and temperature variations, and not suitable for modern communication systems like 5G, which require improved linearity and efficiency.
Innovation Solution
A segmented power amplifier arrangement with feedforward adaptive bias circuits, including separate bias and linearization circuits coupled by a coupling circuit, and an adaptive coupling circuit that adjusts impedance based on input power, to generate bias signals with DC and RF components that adapt to input power levels, optimizing linearity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power amplifiers operate in saturation to achieve highest efficiency, then efficiency is improved, but linearity deteriorates due to increased nonlinear distortions
Solution Approach 1:
The power amplifier is divided into multiple parallel segments (first PA segment and second PA segment), each with its own adaptive bias circuit. This segmentation allows different segments to operate at different power levels and bias conditions, enabling the system to maintain linearity while achieving high efficiency by appropriately combining outputs from segments operating in different regions.
Solution Approach 2:
The patent implements dynamic bias adjustment through adaptive bias circuits that continuously modify bias signals based on real-time operating conditions. The bias signals include DC components and RF components that adapt to input power levels, allowing the amplifier to dynamically transition between linear and saturated operation modes to optimize both linearity and efficiency.
2Object-generated harmful factors
If conventional adaptive biasing techniques are used to improve linearity, then linearity is improved, but sensitivity to process, voltage, and temperature variations worsens
Solution Approach 1:
The adaptive bias circuits incorporate feedback mechanisms that monitor operating conditions and adjust bias signals accordingly. The circuits use feedback from the RF signal path to dynamically compensate for process, voltage, and temperature variations, maintaining stable bias conditions and improving reliability under varying environmental conditions.
Solution Approach 2:
The patent changes the parameters of bias signals by incorporating both DC components and RF components that adapt to input power levels. This parameter modification allows the bias conditions to be optimized for different operating points, reducing sensitivity to PVT variations while maintaining linearity across different power levels.
3Object-generated harmful factors
If back-off is applied to reduce input power for desired linearity, then linearity is improved, but productivity deteriorates due to reduced output power
Solution Approach 1:
By segmenting the power amplifier into multiple parallel paths with different adaptive bias circuits, the system can process different power levels simultaneously. This allows the overall system to deliver high output power while maintaining linearity through the coordinated operation of segments operating at different bias conditions.
Solution Approach 2:
The adaptive bias circuits are designed to provide multiple functions: they adjust bias conditions for linearity optimization, compensate for PVT variations, and enable high efficiency operation. This multi-functionality eliminates the need for separate back-off mechanisms, allowing the amplifier to maintain both linearity and high output power.
Data Source
AI summary
Segmented power amplifier (PA) arrangements are disclosed. An example PA arrangement includes at least first and second PA segments, each having a respective combination of a PA and a feedforward adaptive bias circuit, configured to generate a bias signal for the corresponding PA. Each bias signal has a first DC component, at least one tone component, and at least one harmonic of the at least one tone component. The PA arrangement further includes a power splitting circuit, configured to split an input signal for the PA arrangement into a first PA input signal for the first PA segment and a second PA input signal for the second PA segment, where a power of the first PA input signal is greater than a power of the second PA input signal.