In this thesis, noise modeling of microwave high electron mobility transistors (HEMTs) has been presented. Noise modeling which accounts for thermal noise, shot noise and GR noise shows good agreement at lower GHz frequency range. For detailed noise modeling and characterization, noise parameters are measured and intrinsic noise sources are extracted using correlation matrices. By analyzing the extracted intrinsic noise contribution, the noise source components of HEMT are categorized into three sources - thermal noise, GR noise, and shot noise. Therefore, the proposed noise model takes into account three noise sources independently and the relation between the gate and the drain component of each noise source is expressed using the corresponding correlation coefficient. Especially, the correlation coefficient for GR noise is exploited as an additional fitting parameter. By using the correlation of coefficient, improved noise modeling has been achieved at 2~4 GHz. This proposed modeling is applied to the analyses of InP based HEMT, unpassivated GaN HEMT and passivated GaN HEMT and the results of simulation show good agreement with measured noise parameters at the lower GHz frequency range.
In addition, the dependence of the GR noise on the passivation in GaN HEMT was investigated using the process of noise modeling. By analyzing GR noise sources, it is found that the contribution of GR noise decreases by 45% after passivation in GaN HEMTs.
이 논문에서는 고주파 HEMT의 잡음 모델링이 수행되어졌다. 제안된 잡음 모델링은 열잡음, 산탄 잡음, GR 잡음을 잡음 소스로서 모두 고려하여 좀더 낮은 GHz 주파수 영역에서 측정치와 일치하는 잡음 파라미터의 결과를 보였다. 이러한 모델링과 잡음 특성 분석을 위해서, 잡음 파라미터들이 측정되어지고, 이것들로부터 intrinsic 잡음 소스들이 추출되며, 이 잡음 소스 분석을 통해 GR 잡음을 추출할 수 있게 된다. 결국, GR 잡음의 분석을 통해 소자의 잡음 특성을 파악할 수 있으며, 특히, GaN HEMT에서 passivation 전후에 대한 비교를 통해 그 효과를 연구할 수 있었다.
