Current-Bleeding Balun LNA for Lower Noise and Better Matching
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Solution Overview
Problem
Existing low noise amplifiers (LNAs) in communication devices face issues with noise factor (NF) and mismatch between gain and phase, particularly in CG-CS balun LNAs, which affect their noise characteristics and effectiveness across various frequency bands.
Innovation Solution
Incorporating a current bleeding circuit with a symmetric load and active elements, such as transistors, to enhance the degeneration effect and reduce noise, by connecting the common gate and common source amplifiers with a first and second load, respectively, and utilizing a current bleeding circuit to distribute current and improve impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a CG-CS balun LNA structure is used, then gain and phase can be provided, but noise factor (NF) performance deteriorates due to mismatch between gain and phase
Solution Approach 1:
The LNA is divided into two separate amplifier paths: a common gate amplifier path and a common source amplifier path. Each path processes the signal independently with its own load (first load and second load respectively), allowing independent optimization of each path's characteristics while maintaining overall system performance.
Solution Approach 2:
Different amplifier configurations are applied to different parts of the circuit: the common gate amplifier provides one set of characteristics while the common source amplifier provides another. The first load and second load are independently designed with specific impedance values to optimize local performance, particularly noise factor in each path.
2Power
If existing LNA structures are used, then basic amplification is provided, but impedance matching deteriorates leading to poor noise characteristics
Solution Approach 1:
The impedance values of the first load and second load are specifically adjusted and optimized. By changing the impedance parameters of these loads to predetermined values, the circuit achieves improved impedance matching at the output, which directly enhances noise characteristics and overall performance.
Data Source
AI summary
Disclosed is a low noise amplifier including a current bleeding circuit. The low noise amplifier includes a common gate amplifier, a common source amplifier of which a gate is connected to a source of the common gate amplifier, a symmetric load connected to an output end of the common gate amplifier and an output end of the common source amplifier, and a current bleeding circuit of which one end is connected to the output end of the common source amplifier and another end is connected to the symmetric load, and including an active element and a load corresponding to the symmetric load.