Dual-Path LNA Architecture for Independent Noise and Distortion Cancellation
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Solution Overview
Problem
Traditional low noise amplifiers (LNAs) face challenges in simultaneously achieving low noise and linear operation while minimizing power consumption, often requiring large inductors that are costly and compromise distortion cancellation, with shared compensation circuitry leading to trade-offs between noise and distortion cancellation.
Innovation Solution
The implementation of a dual-path LNA architecture with orthogonal distortion and noise cancellation, where a second path with cancellation circuitry, including a noise cancellation amplifier and a distortion cancellation amplifier, is added in parallel to the main path, allowing independent control and elimination of off-chip inductors, thereby improving overall performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional LNA uses shared compensation circuitry for noise and distortion cancellation, then circuit complexity is reduced, but performance trade-offs occur between noise cancellation and distortion cancellation
Solution Approach 1:
The patent divides the cancellation function into two separate parallel paths: one dedicated to noise cancellation and another dedicated to distortion cancellation. This segmentation allows each path to be independently optimized without compromising the other, resolving the trade-off between noise and distortion cancellation performance while maintaining manageable circuit complexity through modular design.
2Measurement precision
If large inductors are used in traditional LNA, then input matching and noise performance are improved, but distortion cancellation capability deteriorates and cost increases
Solution Approach 1:
The patent extracts the distortion cancellation function from the main LNA path and implements it in a separate parallel path. This allows the main LNA to use large inductors for optimal input matching and noise performance without compromising distortion cancellation, as the distortion cancellation is handled independently in the extracted parallel path.
Solution Approach 2:
The patent introduces a parallel cancellation path as an intermediary structure that handles distortion cancellation separately. This intermediary path includes cancellation circuitry that works in conjunction with the main LNA path but does not interfere with the main path's noise and matching performance, allowing both functions to coexist optimally.
3Productivity
If high frequency operation is implemented for increased data transfer rates, then productivity is improved, but noise and distortion increase
Solution Approach 1:
The patent implements preliminary anti-action by proactively canceling noise and distortion through dedicated cancellation paths before they can degrade the signal quality at high frequencies. The cancellation circuitry generates opposite-phase signals that preemptively counteract the noise and distortion generated by the main LNA path, enabling high-frequency operation with maintained signal integrity.
Data Source
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Figure 2A~2B
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AI summary
Low noise amplifiers (LNAs) are disclosed. In one aspect, an LNA may have distortion cancellation that is orthogonally implemented relative to noise cancellation such that changes to the distortion cancellation do not affect the noise cancellation. In further example aspects, cancellation circuitry is added in parallel to a main or primary LNA path. The cancellation circuitry may include an initial impedance matching amplifier (200B) that effectuates noise cancellation and a second amplifier (202A) that effectuates distortion cancellation. Variations in the placement and composition of the second amplifier are provided. By providing a second path that allows for independent control of noise and distortion cancellation, overall performance of the LNA is improved.