RF Amplifier Circuit With Switchable Inductive Feedback
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Solution Overview
Problem
Existing amplifier circuits face challenges in maintaining high linearity while providing sufficient gain, especially when the strength of the radio-frequency signal varies, as strong magnetic coupling for high linearity leads to reduced gain and vice versa.
Innovation Solution
An amplifier circuit design that includes transistors and inductors with switches to adjust the mutual inductance dynamically, allowing for adaptive feedback based on the signal strength, thereby optimizing gain and linearity according to the input signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If strong magnetic coupling is applied between the two inductors to improve linearity, then linearity is improved, but gain decreases
Solution Approach 1:
The patent applies the dynamics principle by making the magnetic coupling between the two inductors adjustable rather than fixed. Switches are connected to control the coupling coefficient, allowing the system to dynamically change its characteristics based on operating conditions. This resolves the contradiction by enabling strong coupling when linearity is needed and weak coupling when gain is needed, rather than being constrained to a fixed trade-off.
2Power
If weak magnetic coupling is applied between the two inductors to increase gain, then gain is increased, but linearity degrades causing distortion
Solution Approach 1:
The patent applies the dynamics principle by making the magnetic coupling between the two inductors adjustable rather than fixed. Switches are connected to control the coupling coefficient, allowing the system to dynamically change its characteristics based on operating conditions. This resolves the contradiction by enabling strong coupling when linearity is needed and weak coupling when gain is needed, rather than being constrained to a fixed trade-off.
3Manufacturing precision
If fixed strong negative feedback is applied to improve linearity, then linearity is improved, but the amplifier cannot provide sufficient gain for low-strength radio-frequency signals
Solution Approach 1:
The patent applies the dynamics principle by making the negative feedback strength adjustable through switches that control the magnetic coupling between inductors. This allows the amplifier to adapt its feedback level based on the input signal strength, providing strong feedback for linearity when needed and weak feedback for gain when dealing with low-strength signals.
Solution Approach 2:
The patent applies the parameter changes principle by varying the coupling coefficient parameter between the two inductors. By changing this parameter through the switch configuration, the system can adjust the amount of negative feedback to match the operating conditions, thereby adapting to different signal strengths while maintaining optimal performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design enables gain adjustment according to the signal strength while minimizing distortion, maintaining high linearity and gain across varying input signal conditions.
Implementation Method 1
magnetically coupling an inductor connected to a gate of a transistor that is a component of the amplifier to an inductor connected to a source of the transistor to apply negative feedback
Data Source
AI summary
An amplifier circuit includes: a transistor provided between an input terminal and an output terminal and having a gate connected to the input terminal, a source connected to a ground, and a drain connected to the output terminal; an inductor connected between the source and the ground; an inductor connected between the gate and the input terminal, and switches connected to at least one of the inductors and configured to change a mutual inductance of the inductors.