环行器对低噪声放大器性能的改善

基于网络S参数理论,分析了环行器对低噪声放大器性能的影响。设计了一种工作在4.3~5.1GHz的微波晶体管低噪声放大器和铁氧体带线Y结环行器,数值仿真对比了环行器接入前后低噪声放大器的驻波比、稳定性和增益平坦度性能。结果显示接入环行器可以改善放大器的输入匹配,增加稳定性和提高增益平坦度,是一种提高低噪声放大器性能的有效方法。

An Improved Low Noise Amplifier Using Circulator

Based on scattering matrix theory,the performances of a Low Noise Amplifier (LNA) with a circulator is analyzed. A microwave transistor LNA and a Y-junction stripline ferrite circulator with operating bandwidth from 4.3 GHz to 5.1 GHz are designed and simulated. The performance of the LNA with and without the circulator,including the voltage standing wave ratio,the stability and the gain flatness,are compared. Numerical results show that the voltage standing wave ratio,the stability and the gain flatness of the LNA are significantly improved by combing the LNA with the ferrite circulator. It is an effective method to enhance the performances of a LNA.