Sensitivity Analysis Of Parameters And Microwave Performance For InP HBT Small-signal Model

The equivalent circuit model of semiconductor devices is the basis of integrated circuit(IC)designs.The selection and application of device model are very important in the designs of power amplifiers,filters,oscillators and mixers.Heterojunction bipolar transistor(HBT),which based on indium phosphorus(In P)material system,has great advantages and development potentials in high-frequency applications.Under the condition of moderate cost,In P HBT attractes more and more attentions in the millimeter wave field.The accuracy of the model often depends on the reliability of model parameter extraction.There are many methods to extract the parameters of small-signal equivalent circuit of HBT devices.This paper mainly presents the direct extraction method of intrinsic parameters.The method of direct extraction is easy-to-understand as well as fast-speed.However,further optimization measures are often needed to ensure the accuracy of parameters and the estimation of models'stability.In this paper,a sensitiveity analysis method is proposed for estimating the uncertainty of small signal model.The method can be used to assist in determining the optimal values of intrinsic parameters extraction.Based on In P HBT devices,the sensitivities of small-signal equivalent model parameters is presented,and the microwave performances of the device are analyzed by Monte-Carlo methods.The main contents of this paper are as follows:1)The basic structures of small-signal model of HBT devices and the direct extraction method of model parameters are introduced;2)Based on the formulas of direct extraction method,the sensitivity expressions of intrinsic parameters to S-parameters in small-signal equivalent circuit is derived;3)Combined with the measurement uncertainties of the vector network analyzer,the uncertainties of intrinsic parameters to measured S-parameters is obtained;4)Based on the5?5?m~2In P HBT,the measured S-parameters are compared with the simulated S-parameters for the optimized model.The results show that the S-parameters fit well in the frequency range of 450MHz-40GHz under different bias conditions;5)Using the minimum uncertainty obtained from sensitivity analysis,the current gain cut-off frequency and maximum oscillation frequency of HBT microwave performances are analyzed by Monte Carlo methods.