Low-Noise Amplifier Circuit With Distortion Cancellation for Adjacent Bands
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Solution Overview
Problem
Conventional low noise amplifiers (LNAs) generate harmonic and intermodulation distortions that interfere with adjacent RF bands, particularly the 5G ultra-high-band, and existing solutions either fail to suppress these distortions effectively or compromise the overall noise figure.
Innovation Solution
Incorporating a distortion amplifier in parallel with the LNA to generate a distortion signal that cancels out harmonic and intermodulation distortions in the RF output signal, using combiner circuitry to combine the RF output with the distortion signal, thereby protecting adjacent bands without affecting the noise figure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional LNA is used to amplify RF input signal, then the RF output signal is amplified, but harmonic and intermodulation distortions are generated that interfere with adjacent RF bands
Solution Approach 1:
The patent generates distortion signals that replicate the harmonic and intermodulation distortions produced by the LNA, then combines these distortion signals with the LNA output. By adding the distortion signals in opposite phase, the harmful distortions are canceled out, converting the problem of distortion generation into a solution through deliberate distortion signal injection and phase cancellation.
Solution Approach 2:
The patent applies preliminary anti-action by generating distortion signals before they interfere with adjacent bands and combining them with the LNA output in opposite phase. This preemptive cancellation approach prevents the harmful distortions from affecting adjacent RF bands while maintaining the desired signal amplification.
2Object-generated harmful factors
If distortion suppression techniques are applied to reduce harmonic and intermodulation distortions, then adjacent RF bands are protected, but the noise figure of the LNA is compromised
Solution Approach 1:
The patent segments the signal processing function into two separate paths: the main LNA path for signal amplification and the distortion signal generation path for distortion cancellation. By separating these functions and combining them through the combiner circuitry, the system achieves distortion suppression without the distortion suppression circuit directly degrading the noise figure of the main amplification path.
Data Source
AI summary
Embodiments of the disclosure relate to a low noise amplifier (LNA) circuit. The LNA circuit includes an LNA configured to amplify a radio frequency (RF) input signal to generate an RF output signal. The LNA may be inherently nonlinear and, as a result, can create a harmonic distortion(s), such as second harmonic distortion (HD2), and/or an intermodulation distortion(s), such as second order intermodulation distortion (IMD2), in the RF output signal. In exemplary aspects discussed herein, a distortion amplifier(s) is provided in the LNA circuit to generate a distortion signal(s) to suppress the harmonic distortion(s) and/or the intermodulation distortion(s) in the RF output signal. By suppressing the harmonic distortion(s) and/or the intermodulation distortion(s) in the RF output signal, the LNA circuit may protect an adjacent RF band(s), such as the fifth-generation ultra-high-band (5G UHB), from the harmonic and/or intermodulation distortion(s) without compromising overall noise figure (NF) of the LNA circuit.