Magnetically Coupled Inductor Matching for Linear Low-Noise Amplifiers
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Solution Overview
Problem
Low noise amplifiers (LNAs) face challenges in achieving high linearity while maintaining low supply current, which is essential for various electronic systems, particularly in RF applications, as existing technologies struggle to optimize linearity and noise performance simultaneously.
Innovation Solution
The implementation of an impedance transformation circuit with magnetically coupled inductors, specifically a degeneration inductor and a series input inductor, provides negative feedback to linearize the amplifier, allowing for improved linearity by controlling the input match and utilizing both self and mutual inductance effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LNA designs are used, then noise performance can be maintained, but linearity is degraded
Solution Approach 1:
The patent applies negative feedback through magnetic coupling between inductors to linearize the amplifier. The feedback mechanism reduces the gain of the amplification circuit while improving linearity, specifically enhancing the 1 dB compression point and 3rd order intermodulation performance without significantly degrading noise performance
Solution Approach 2:
The patent transforms the inductors into an impedance transformation circuit that changes the operating parameters of the amplification circuit. By configuring inductors as impedance transformation elements rather than simple matching components, the circuit achieves both input matching and linearity improvement simultaneously
2Reliability
If linearity is improved through conventional methods, then 1 dB compression point can be enhanced, but supply current increases
Solution Approach 1:
The negative feedback mechanism improves linearity through impedance transformation rather than gain reduction alone. The feedback network configured with inductors provides linearity enhancement while maintaining higher supply current performance compared to conventional feedback approaches
Solution Approach 2:
The inductors serve multiple functions simultaneously: input matching, impedance transformation, and linearity improvement. This multi-functionality eliminates the need for separate circuits for each purpose, reducing overall supply current consumption
3Ease of manufacture
If on-chip inductors are used for impedance matching, then integration is improved, but noise performance is degraded
Solution Approach 1:
The patent changes the functional parameters of on-chip inductors from simple matching elements to impedance transformation circuit elements. This transformation allows the inductors to provide both matching and linearity improvement functions, reducing the need for additional noisy components while maintaining integration benefits
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
This approach enhances the 1 dB compression point and 3rd order intermodulation performance of LNAs, enabling better linearity while potentially reducing the noise performance impact of on-chip inductors, thus meeting stringent specifications for linearity and noise performance.
Implementation Method 1
The first and second inductors are magnetically coupled to each other to provide negative feedback to linearize the amplifier
Data Source
AI summary
Aspects of this disclosure relate to an impedance transformation circuit for use in an amplifier, such as a low noise amplifier. The impedance transformation circuit includes a matching circuit including a first inductor. The impedance transformation circuit also includes a second inductor. The first and second inductors are magnetically coupled to each other to provide negative feedback to linearize the amplifier.