Balanced Amplifier Power Back-Off With Switched Impedance Tuning
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Solution Overview
Problem
Balanced amplifiers operating in power back-off conditions are less efficient, leading to increased power dissipation and thermal challenges due to the constant DC power consumption, which is not reduced by simply reducing the input RF power.
Innovation Solution
The amplifier arrangement operates in two modes: a balanced mode and a single-ended mode, where one amplifier is deactivated to reduce DC power consumption, and impedance coupling is adjusted to tune the frequency response, allowing for reduced output power while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the input RF power is reduced to achieve power back-off conditions, then the output power is reduced, but the DC power consumption remains constant leading to reduced efficiency
Solution Approach 1:
The patent applies dynamics by making the amplifier configuration adjustable between balanced and single-ended modes. The system dynamically switches between two amplifier paths based on operating conditions, allowing the DC power consumption to be reduced when operating in power back-off conditions by deactivating one amplifier path while maintaining proper impedance matching through the couplers.
Solution Approach 2:
The patent changes the operational parameters of the amplifier system by switching between different modes (balanced vs. single-ended). By adjusting which amplifier path is active and how the couplers are configured, the system can operate efficiently at both high and low output power levels, resolving the contradiction between reduced output power and maintained efficiency.
2Reliability
If both amplifiers are kept active to maintain balanced operation, then linearity is improved, but DC power dissipation increases
Solution Approach 1:
The patent applies partial action by activating only one amplifier path when full balanced operation is not required. In power back-off conditions, the system can achieve sufficient linearity with a single active amplifier path, reducing DC power dissipation by keeping one amplifier inactive while still meeting performance requirements.
Solution Approach 2:
The system dynamically adjusts the number of active amplifier paths based on operating conditions. During high power operation, both amplifiers are active to provide balanced operation and improved linearity. During power back-off conditions, the system switches to single-ended operation with one amplifier deactivated, reducing power dissipation while maintaining acceptable performance.
3Loss of energy
If one amplifier is deactivated to reduce power consumption, then DC power dissipation is reduced, but impedance matching becomes unbalanced
Solution Approach 1:
The couplers serve as intermediaries that maintain proper impedance matching even when one amplifier is deactivated. The couplers are designed to transform the impedance seen by the active amplifier and the terminated port, ensuring that the system maintains stable impedance characteristics regardless of whether one or both amplifiers are active.
Solution Approach 2:
The couplers perform multiple functions: they split/combine signals during balanced operation and provide impedance transformation during single-ended operation. This multi-functionality allows the same hardware structure to maintain proper impedance matching across different operational modes, resolving the contradiction between reduced power consumption and maintained impedance stability.
Data Source
AI summary
Methods and apparatuses for providing a reduction in output power of a balanced amplifier configuration are presented. According to one aspect, reduction of the output power is provided by deactivating one of the two amplification paths of the balanced amplifier. According to another aspect, impedances seen at ports of input and output couplers of the balanced amplifier configuration part of a deactivated amplification path are selectively switched in dependence of operation according to the reduced output power or according to normal output power. In addition, or in the alternative, impedance seen at an isolated/terminated port of the input and/or the output coupler is selectively switched in dependence of the operation. When operating according to the reduced output power, values of the switched impedances can be adjusted to tune a frequency response of the balanced amplifier.