Corrective Feedback Power Amplifier Control for GSM and EDGE
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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 methodologies, leading to power consumption issues and potential saturation, especially when using nonlinear power amplifiers for both GSM and EDGE modes.
Innovation Solution
A low delay corrective feedback power amplifier control system with multiple control loops is implemented, including an outer AM correction loop, inner AM correction loop, and phase correction loop, to independently control amplitude and phase modulation, minimizing distortion and maintaining stability across varying bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear power amplifier is used for non-constant envelope modulation (EDGE), then amplitude and phase modulation accuracy is improved, but power consumption increases significantly
Solution Approach 1:
The patent segments the control function into multiple independent control loops: an outer AM correction loop for amplitude control and an inner phase correction loop for phase control. This segmentation allows the nonlinear power amplifier to be controlled with the precision of a linear amplifier while maintaining the efficiency benefits of nonlinear operation.
Solution Approach 2:
The patent implements feedback mechanisms in both the outer AM correction loop and inner phase correction loop. The feedback paths monitor the actual output and adjust the control signals to minimize distortion, enabling accurate amplitude and phase modulation while using a more efficient nonlinear power amplifier.
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 accuracy deteriorates when used for non-constant envelope modulation (EDGE)
Solution Approach 1:
The patent makes the control system dynamic by implementing multiple control loops with different bandwidths. The outer AM correction loop operates with a wider bandwidth to handle amplitude variations, while the inner phase correction loop operates with a narrower bandwidth to maintain phase stability. This dynamic control structure allows the nonlinear power amplifier to accurately handle both constant and non-constant envelope modulations.
Solution Approach 2:
The patent changes the control parameters by separately controlling amplitude and phase through different loops. The outer loop controls the amplitude parameter while the inner loop controls the phase parameter, allowing independent optimization of each parameter to achieve high modulation accuracy with a nonlinear power amplifier.
3Measurement precision
If multiple control loops are implemented for low delay corrective feedback, then control precision is improved, but system complexity increases
Solution Approach 1:
The patent segments the control system into distinct functional blocks: an outer AM correction loop with its own feedback path and an inner phase correction loop with its own feedback path. Each segment handles a specific control function, which simplifies the design and analysis of the overall system while achieving high control precision through the coordinated operation of multiple segments.
Data Source
AI summary
A system for controlling the power output of a power amplifier includes a power amplifier through 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, a feedback signal comprising a portion of the output of the power amplifier, a first control loop configured to receive the feedback signal and configured to apply an amplitude modulated (AM) signal to the power amplifier and configured to control the gain of the power amplifier, a second control loop configured to receive the feedback signal and configured to correct for offsets in the forward path and to linearize the first control loop; and a third control loop configured to receive the feedback signal and configured to control the phase of the PM component of the transmit signal.