Variable-Impedance Bias Coupling for Amplifier Linearity
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Solution Overview
Problem
Conventional bias circuits for power amplifiers, particularly adaptive bias circuits, introduce nonlinearity that degrades the linearity of power amplifiers, and using fixed coupling components to mitigate this issue can degrade power and efficiency.
Innovation Solution
A bias network with an adaptive coupling circuit that modifies the bias signal by varying impedance based on the input power level, reducing nonlinearity and optimizing the bias signal for improved amplifier linearity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fixed coupling component is used to connect the bias circuit to the amplifier, then nonlinearity introduced by the bias circuit is reduced, but power and efficiency are degraded
Solution Approach 1:
The patent applies the dynamics principle by transforming the fixed coupling component into a variable impedance coupling circuit that dynamically adjusts its characteristics based on operating conditions. The coupling circuit includes control logic that modifies the impedance between the bias circuit and amplifier input according to the amplifier's operating state, thereby optimizing both linearity and power efficiency under different conditions rather than being constrained by a fixed design.
Solution Approach 2:
The patent implements parameter changes by varying the impedance parameters of the coupling circuit based on the power level of the input signal. The system monitors the operating conditions and adjusts the coupling parameters dynamically, allowing the bias circuit to maintain optimal performance across different power levels without being locked into a single fixed configuration that compromises either linearity or efficiency.
2Manufacturing precision
If the impedance of the coupling circuit is increased to reduce nonlinearity, then linearity improves, but power and efficiency are degraded
Solution Approach 1:
The system dynamically adjusts the impedance of the coupling circuit based on real-time monitoring of the amplifier's operating conditions. Rather than maintaining a permanently high impedance to ensure linearity, the system adapts the impedance level according to the current power level and operating state, thereby maintaining efficiency while achieving linearity when needed.
Solution Approach 2:
The patent changes the impedance parameter of the coupling circuit as a function of the input signal power level. The control logic modifies the coupling parameters to optimize the trade-off between linearity and efficiency, allowing the system to achieve high linearity when required while maintaining good efficiency under other operating conditions through parameter adaptation.
3Power
If the impedance of the coupling circuit is decreased to improve power and efficiency, then power and efficiency improve, but nonlinearity increases
Solution Approach 1:
The system dynamically adjusts the coupling impedance based on the amplifier's operating state. When high power and efficiency are the primary requirements, the system decreases the impedance to improve performance. When linearity becomes critical, the system increases the impedance accordingly. This dynamic adaptation allows the system to optimize for different performance criteria based on real-time conditions rather than being constrained by a fixed impedance design.
Solution Approach 2:
The patent implements parameter changes by adjusting the impedance of the coupling circuit as a function of the input signal power level and operating conditions. The control logic modifies the coupling parameters to achieve the desired balance between power efficiency and linearity, allowing the system to operate at high efficiency when linearity requirements are lower and maintain linearity when required, rather than being locked into a suboptimal fixed configuration.
Data Source
AI summary
Bias networks for amplifiers are disclosed. An example bias network includes an adaptive bias circuit, configured to generate a bias signal for an amplifier, and further includes a coupling circuit, configured to couple the adaptive bias circuit to the amplifier. The coupling circuit is made adaptive in that its' impedance depends on a power level of an input signal to be amplified by the amplifier. By configuring the coupling circuit to have a variable impedance that depends on the power level of the input signal, the coupling circuit may adapt to the input power level and, thereby, may modify the bias signal to reduce/optimize at least some of the nonlinearity that may be introduced to the bias signal by the adaptive bias circuit.