Modeling Of GaN HEMTs High Frequency Equivalent Noise Circuit

With the increase of applicable frequency of modern communication system,higher index transistor devices are needed in RF and microwave circuit design,and the third generation semiconductor transistor GaN HEMTs have the advantages of higher electron saturation rate and lower dielectric constant.There are significant differences in the analysis and characterization of high frequency noise mechanisms in FET devices under different production processes.In order to effectively characterize the electrical properties of GaN HEMTs in the microwave frequency band,this paper focuses on the modeling of high frequency equivalent noise circuits of GaN HEMTs and carries out the following work:Firstly,Establish GaN HEMTs small signal equivalent circuit model.Based on the analysis of the physical structure of GaN HEMTs devices,this paper establishes a small-signal equivalent circuit model with 26 detailed parameters for the parasitic effects triggered by the connected electrodes and through-hole parts of the devices during the plate-making process,which takes into account the skin effect of the devices during operation and characterizes the correlation between the resistance value and frequency.The direct parameter extraction method is given after establishing a small-signal equivalent circuit model of GaN HEMTs based on skinning effect,and the extracted parameters have some physical significance because no algorithm optimization is used.Secondly,the GaN HEMTs high frequency noise equivalent circuit model is established.This paper uses the characterization method of two-port noise correlation matrix to extract the gate induction noise and drain channel noise power spectral density inside GaN HEMTs by using the actual measurement results of the four noise parameters of GaN HEMTs,and then establishes the improved temperature noise model and PRC model based on the power spectral density,this model is more traditional than the model based on the consideration of the device by the inter-pole resistance R_gdand This model is based on the traditional model,which takes into account the influence of inter-pole resistance R_gdand inter-pole capacitance C_gd,so that the introduction of the real part of the noise factor C in the PRC noise model leads to the frequency-dependent characteristics of the imaginary part of the relevant noise power spectral density,while the noise generated by the intrinsic part of the inter-pole resistance R_gdneeds to be considered in the temperature noise model,and the detailed noise de-embedding process and noise parameter extraction method are given for the above improved model.Finally,to validate the established small-signal equivalent circuit model and high-frequency noise equivalent circuit model of GaN HEMTs.The GaN HEMTs small signal equivalent circuit model,the improved PRC noise equivalent circuit model,and the temperature noise equivalent circuit model with gate length of 0.25um,gate width of(4×50)um and(8×50)um processes are embedded in the ADS software for simulation,and the consistency of the simulation results and measured data are compared with the control variable method to verify that the noise performance of the two different structures of the GaN HEMTs can be simulated with high accuracy using the improved PRC noise model and the improved temperature noise model,respectively.The noise performance of GaN HEMTs devices with two different structures can be simulated with the improved PRC noise model and the improved temperature noise model with high accuracy,and the minimum noise coefficient fit of the improved noise model is improved compared with that of the conventional model.The accuracy of the established model and the effectiveness of the parameter extraction algorithm are further demonstrated.