Cross-Coupled Inductive LNA Circuit for Lower Noise Figure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Low noise amplifiers in wireless receiving systems introduce noise due to field effect transistors, leading to inaccurate data extraction, and existing solutions are costly and ineffective in improving noise figures.
Innovation Solution
A signal amplifying circuit with an input stage, first inductive element, and second inductive element, where at least part of the winding of the first inductive element is cross-coupled to part of the winding of the second inductive element, reducing noise by introducing a coupling effect and inversely proportional noise figure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If field effect transistors are used in the low noise amplifier, then the amplifier can be implemented with standard components, but the noise figure increases due to channel noise and gate noise coefficients
Solution Approach 1:
The patent introduces an inductive element as an intermediary component between the field effect transistor and the output. This inductive element acts as a mediator that couples the noise from the transistor to the output in a controlled manner, allowing the noise to be managed and reduced while still using standard field effect transistor components.
Solution Approach 2:
The patent changes the electrical parameters of the circuit by introducing inductive coupling. By adjusting the inductance values and coupling coefficients, the noise figure is optimized. The inductive element transforms the noise characteristics through its impedance and coupling properties, reducing the overall noise figure while maintaining component standardization.
2Object-affected harmful factors
If the noise figure is reduced by using advanced components or complex circuits, then the data extraction accuracy improves, but the cost and circuit complexity increase
Solution Approach 1:
The patent segments the low noise amplifier into distinct functional stages: an input stage with the field effect transistor, an inductive coupling stage with the inductive element, and an output stage. This segmentation allows each stage to be optimized independently, reducing overall noise figure without requiring complete redesign of the entire circuit.
Solution Approach 2:
The inductive element serves as an intermediary stage that simplifies the noise reduction approach. Instead of using complex active noise cancellation circuits, the passive inductive coupling provides noise management through its inherent electrical properties, reducing circuit complexity while improving noise figure.
3Object-affected harmful factors
If the inductive elements are cross-coupled to reduce noise, then the noise figure improves and circuit area is minimized, but the circuit design complexity increases
Solution Approach 1:
The patent merges the functions of noise reduction and space efficiency by cross-coupling the inductive elements. The same inductive elements that provide noise coupling are arranged in a cross-coupled configuration that simultaneously minimizes the circuit area. This merging of functions achieves multiple goals without adding separate components.
Solution Approach 2:
The cross-coupled configuration utilizes spatial arrangement in a clever manner, effectively using the physical layout dimension to achieve noise reduction. By positioning and coupling the inductive elements in specific spatial relationships, the patent reduces noise figure while minimizing the area occupied by the circuit.
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 cross-coupling of inductive elements in the signal amplifying circuit reduces noise introduced by field effect transistors, improving the noise figure and maintaining low costs by minimizing circuit area.
Implementation Method 1
at least a part of the winding of the first inductive element is cross-coupled to at least a part of the winding of the second inductive element
Data Source
AI summary
A signal amplifying circuit includes: an input stage circuit, arranged to receive an input signal; a first inductive device coupled between the input stage circuit and a first reference voltage; an output stage circuit arranged to generate an output signal according to the input signal; and a second inductive device coupled between the output stage circuit and a second reference voltage, wherein at least a part of a winding of the first inductive element is cross-coupled to at least a part of a winding of the second inductive element.