Power Amplifier Bias Switching for Lower Nonlinear Distortion
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Solution Overview
Problem
Existing power amplifier circuits face limitations in reducing nonlinear distortion when supplied with multiple discrete voltages, despite the use of digital pre-distortion techniques.
Innovation Solution
A power amplifier circuit design that includes multiple power amplifiers and bias circuits, where bias voltages are adjusted in proportion to the power supply voltage, allowing for dynamic adjustment to reduce nonlinear distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multiple discrete voltages are supplied to the power amplifier circuit to improve power-added efficiency, then power consumption is reduced, but nonlinear distortion increases and cannot be adequately suppressed by digital pre-distortion
Solution Approach 1:
The bias voltage is dynamically adjusted in synchronization with the power supply voltage changes. When the power supply voltage switches between multiple discrete levels, the bias voltage corresponding to each power amplifier stage is switched to appropriate values, thereby dynamically adapting the operating point to maintain linearity across different power levels and suppress nonlinear distortion effectively
Solution Approach 2:
The invention changes the bias voltage parameter in response to power supply voltage changes. By switching the bias voltage to different values corresponding to different power supply levels, the operating characteristics of the power amplifiers are adjusted, enabling effective suppression of nonlinear distortion while maintaining the benefits of multiple discrete voltage operation
2Reliability
If digital pre-distortion is used to reduce nonlinear distortion, then signal quality improves, but the effectiveness is limited when multiple discrete voltages are applied
Solution Approach 1:
The bias voltage is preliminarily adjusted to appropriate values before the power amplifier operates at each discrete power supply level. This preliminary setting of the operating point ensures that the power amplifier starts from an optimal linear operating condition for each voltage level, enhancing the overall effectiveness of distortion suppression
Solution Approach 2:
The system incorporates feedback mechanisms where the power supply voltage level is detected and used to control the bias voltage switching. This feedback loop ensures that the bias voltage is always at the appropriate value for the current power supply level, maintaining signal quality and linearity across all operating conditions
Data Source
AI summary
A power amplifier circuit includes a first power amplifier that amplifies a radio frequency signal using multiple discrete voltages; a second power amplifier that amplifies the radio frequency signal; a bias circuit that supplied a first bias voltage to the first power amplifier when a first power supply voltage is supplied to the first power amplifier and a second bias voltage lower than the first bias voltage to the first power amplifier when a second power supply voltage higher than the first power supply voltage is supplied to the first power amplifier; and a bias circuit that supplied a third bias voltage to the second power amplifier when the first power supply voltage is supplied to the second power amplifier and a fourth bias voltage higher than the third bias voltage to the second power amplifier when the second power supply voltage is supplied to the power amplifier.