Power Amplifier Bias Tracking With Online Predistortion Feedback
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Solution Overview
Problem
Existing power amplifiers in wireless communication devices face challenges in efficiently amplifying signals while minimizing power consumption, particularly due to the need for factory calibration which is costly and does not account for variations in performance due to temperature and frequency changes.
Innovation Solution
The method involves using online feedback to determine a predistortion and adjust the bias voltage of a power amplifier, allowing for operation at a lower bias voltage without factory calibration. This process includes amplifying an input signal, obtaining an output signal, determining predistortion based on the output signal, applying the predistortion, and amplifying the predistorted signal at a reduced bias voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If factory calibration is performed to ensure power amplifier performance, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
The power amplifier performs self-calibration by using its own output signal as feedback to automatically adjust and optimize its performance characteristics, eliminating the need for external factory calibration equipment and procedures
Solution Approach 2:
The system implements a feedback mechanism where the output signal of the power amplifier is monitored and used to automatically adjust operating parameters such as bias voltage and predistortion coefficients, enabling real-time performance optimization without manual calibration
2Use of energy by moving object
If bias voltage is reduced to lower power consumption, then energy efficiency is improved, but signal quality and linearity deteriorate
Solution Approach 1:
The system applies predistortion to the input signal before amplification to pre-compensate for expected nonlinearities and distortion that would occur at reduced bias voltages, thereby maintaining signal quality while operating at lower power consumption levels
Solution Approach 2:
The system dynamically adjusts operating parameters including bias voltage, predistortion coefficients, and compression point settings to optimize the trade-off between power consumption and signal quality based on real-time operating conditions
3Ease of operation
If fixed bias voltage is used to simplify circuit operation, then ease of operation is improved, but adaptability to temperature and frequency changes deteriorates
Solution Approach 1:
The system transitions from fixed bias voltage to dynamic bias voltage control where the bias voltage automatically adjusts based on real-time feedback from the output signal, enabling the circuit to adapt to temperature and frequency variations while maintaining simple operation through automated control
Data Source
AI summary
Aspects of the present disclosure provide signal amplification. An example method generally includes amplifying a version of a first input signal with a power amplifier in a first state where a bias voltage of the power amplifier is set to a first voltage based on a first tracking mode; obtaining a first output signal of the power amplifier in a second state where the bias voltage is set to a second voltage less than the first voltage; determining a predistortion associated with the power amplifier based at least in part on the obtained first output signal; applying the predistortion to the first input signal; and amplifying a version of the predistorted first input signal with the power amplifier in a third state where the bias voltage is set to a third voltage based on a second tracking mode, wherein the third voltage is less than the first voltage.