Switchable-Inductor Multi-Gain LNA for Wideband Output Matching
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Solution Overview
Problem
Conventional low-noise amplifier (LNA) architectures face limitations in achieving high gain and wideband output impedance matching, particularly in high-frequency applications such as 5G mobile network bands and millimeter wave ranges, due to tradeoffs between gain, bandwidth, and linearity.
Innovation Solution
A multi-gain mode LNA architecture that selectively inserts an inductor between the amplified-signal terminal and the output LC matching network, allowing for wideband output impedance matching and high gain in a highest gain mode, while switching to lower gain modes for improved linearity with reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single-stage LC output impedance matching circuit is used, then high gain can be achieved, but the bandwidth is limited and output impedance matching is narrowband
Solution Approach 1:
The patent applies dynamics by making the inductor configuration switchable between series and parallel connections through control switches. This allows the LNA to dynamically adjust its output impedance matching characteristics across different frequency ranges, achieving wideband matching while maintaining high gain. The series inductor configuration provides high impedance for high-gain operation, while the parallel configuration provides low impedance for bandwidth extension.
Solution Approach 2:
The patent changes the impedance parameters of the output matching circuit by switching between series and parallel inductor configurations. This parameter change enables the circuit to adapt to different frequency bands and impedance requirements, achieving both high gain and wide bandwidth by adjusting the effective inductance and impedance levels.
2Adaptability or versatility
If a two-stage LC output impedance matching circuit is used to achieve wider bandwidth, then gain is reduced and linearity deteriorates due to increased loss
Solution Approach 1:
Instead of using a fixed two-stage LC matching circuit that inherently introduces loss, the patent employs a dynamic switching mechanism that selectively engages series or parallel inductor configurations. This dynamic approach achieves bandwidth extension without the cumulative loss of multiple cascaded LC stages, thereby maintaining high gain and improved linearity.
Solution Approach 2:
The patent extracts the essential bandwidth-extending function from the lossy two-stage LC architecture and implements it through a simpler switched inductor configuration. By removing unnecessary LC stages and retaining only the critical inductive elements with switching control, the design achieves wide bandwidth without sacrificing gain or linearity.
3Power
If the inductor is always connected in series for high gain, then noise figure is low, but linearity is poor in low-gain modes
Solution Approach 1:
The patent implements dynamic switching between series and parallel inductor configurations based on the desired operating mode. In high-gain modes, the series configuration is engaged for optimal noise figure and gain. In low-gain modes requiring better linearity, the parallel configuration is activated to provide different impedance characteristics that improve linearity performance. This dynamic adaptation resolves the contradiction between gain and linearity.
Solution Approach 2:
The patent changes the impedance parameters by switching inductor configurations. The series configuration provides high impedance suitable for high-gain, low-noise operation, while the parallel configuration provides low impedance suitable for high-linearity, low-gain operation. This parameter switching enables the LNA to optimize both gain and linearity according to operational requirements.
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 solution achieves wideband output impedance matching and high gain while maintaining low noise figure in a highest gain mode, and can switch to lower gain modes for higher linearity, effectively addressing the limitations of conventional LNAs in high-frequency applications.
Implementation Method 1
A multi-gain mode LNA architecture that selectively inserts an inductor between the amplified-signal terminal and the output LC matching network
Implementation Method 2
A multi-gain mode LNA architecture that selectively inserts an inductor between the amplified-signal terminal and the output LC matching network, allowing for wideband output impedance matching and high gain in a highest gain mode, while switching to lower gain modes for improved linearity
Data Source
AI summary
Circuits and methods for a multi-gain mode amplifier, particularly an LNA, that achieves wideband output impedance matching and high gain while maintaining low power and a low NF in a highest gain mode, and which can switch to one or more lower gain modes that achieve higher linearity with lower power. In a highest gain mode, an inductor is selectively inserted between the amplified-signal terminal of an amplification core and an output LC output matching network. The inductor, when inserted, provides wideband output impedance matching, functioning as a series peaking inductor; accordingly, the inserted inductor delays current flow to the output capacitor and lowers the rise time of signal changes across the output capacitor. In addition, higher gain can be achieved compared to a conventional LC output impedance matching topology due to a higher impedance at the amplified-signal terminal of the amplification core.