Replica Linearized Power Amplifier With Closed-Loop AM-PM Correction
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Solution Overview
Problem
Existing power amplifiers in portable communication devices face inefficiencies when switching between constant and non-constant envelope modulation methods, leading to power consumption issues and potential saturation, especially when using nonlinear power amplifiers for both GSM and EDGE modes.
Innovation Solution
A replica linearized power amplifier with a forward path and additional amplification device provides proportional output control, utilizing closed-loop feedback to minimize distortion and maintain linear control, incorporating inner and outer AM correction loops and a phase correction loop to stabilize the power amplifier operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear power amplifier is used for non-constant envelope modulation (EDGE), then modulation accuracy is improved, but power efficiency deteriorates
Solution Approach 1:
The patent implements feedback mechanisms including an amplitude feedback loop that detects the output amplitude of the power amplifier and adjusts the input amplitude accordingly, and a phase feedback loop that corrects phase distortion. This feedback approach allows the nonlinear power amplifier to achieve linear modulation characteristics, resolving the contradiction between modulation accuracy and power efficiency.
Solution Approach 2:
The patent separates the modulation control into independent amplitude and phase components. The amplitude modulation is controlled through a dedicated amplitude control signal, while phase modulation is handled separately through phase correction. This segmentation allows the nonlinear power amplifier to process each component efficiently while maintaining overall modulation accuracy.
2Use of energy by moving object
If a nonlinear power amplifier is used for constant envelope modulation (GSM), then power efficiency is improved, but modulation capability deteriorates
Solution Approach 1:
The patent designs a universal power amplifier system that can handle both constant envelope (GSM) and non-constant envelope (EDGE) modulation modes. The system includes configurable amplitude and phase control paths that can be activated or deactivated depending on the modulation mode, allowing the same hardware to efficiently support multiple modulation schemes.
Solution Approach 2:
The patent implements dynamic control mechanisms where the amplitude and phase control loops are actively adjusted based on the operating mode. In GSM mode, the amplitude control is simplified for constant envelope operation, while in EDGE mode, both amplitude and phase controls are fully active to handle variable envelope modulation, optimizing performance for each mode.
3Reliability
If closed-loop feedback is implemented for amplitude and phase control, then linear control is improved, but system complexity increases
Solution Approach 1:
The patent divides the feedback system into separate amplitude control and phase control loops. Each loop handles a specific aspect of modulation independently, with the amplitude loop managing output amplitude linearity and the phase loop correcting phase distortion. This segmentation reduces the complexity of each individual loop while achieving comprehensive linear control.
Solution Approach 2:
The patent introduces intermediary control signals and detection mechanisms that simplify the feedback process. An amplitude detector extracts the amplitude component from the output signal, and separate phase detection mechanisms process phase information. These intermediaries transform complex feedback requirements into manageable control signals, reducing overall system complexity.
Data Source
AI summary
A power amplifier includes a power amplifier core in which a transmit signal having an amplitude-modulated (AM) component and a phase-modulated (PM) component is passed and amplified, the power amplifier comprising a forward path, and an additional amplification device configured to generate an output that is proportional to an output of the power amplifier core, such that the output of the additional amplification device indirectly controls the output of the power amplifier core.