Millimeter-Wave Device Modeling And Parameter Extraction Of ?-? Compounds-Based Heterojunction Bipolar Transistors

?-? compound-based heterojunction bipolar transistors have been widely used in radio frequency,microwave and millimeter-wave circuits due to the superior capability in both high electron mobility and high power density.An accurate physical model of InP HBT plays an important role in circuit design,process technology evaluation and model optimization,which can improve the success rate of monolithic integrated circuit design and shorten the circuit development cycle.The device modeling and parameter extraction of ?-? compound-based heterojunction bipolar transistors at millimeter-wave frequencies have been demonstrated in this thesis.The important findings from this investigation are provided as follows:1)A method to determine the PAD capacitances considering the distribution effect of the base and collector feedlines for HBT devices is proposed.The analytical expressions for the parasitic capacitance and the device emitter area are derived.The extrinsic capacitances can be extracted by utilizing the different size heterojunction bipolar transistors with the same pad profile.The proposed method is verified by Ga As HBT devices in the frequency ranges of 0.1-40 GHz.A direct extraction method to determine the extrinsic resistances based on T-? transformation is proposed.This method simplifies the calculation of model parameters and the extrinsic resistances can be extracted directly by utilizing a set of closed-form expressions.The proposed method is verified by InP HBT devices in the frequency ranges of 2-110 GHz.The results show that good agreement can be obtained between the measured data and the modeled data.Compared with the conventional de-embedding method,the proposed extrinsic capacitances extraction method can effectively save chip areas and test time.The proposed extrinsic resistances extraction method can separate intrinsic and extrinsic base resistance and avoid the effect of temperature changes.2)A parameter-extraction approach to determine the intrinsic elements of small-signal equivalent circuit model for HBT devices is proposed.This method combines the advantages of conventional T-and ?-type equivalent circuit topologies.The intrinsic elements are only extracted analytically from S-parameter data.The results show that good agreement between the measured S parameters and modeled S parameters is obtained for InP HBT devices in the frequency ranges of 0.1-110 GHz.The analytical expressions of the cut-off frequency and maximum oscillation frequency of the HBT devices are derived.InP and Ga As HBT devices are used to verify the accuracy of the parameter extraction analytical expressions.The results show that the measured data are in agreement with the calculation data which predicted by utilizing the derived analytical expressions.3)A nonlinear model of the InP HBT devices including DC/AC dispersion effect is proposed.The effect of frequency dispersion of common-emitter current gain causes significant differences between the DC I-V characteristic and an RF I-V characteristic is solved.The results show that for InP HBT devices,the RF modeled data are in excellent agreement with the RF calculated data,showing the accuracy of the dispersion model.In the frequency range of 0.05-110 GHz,compared with the conventional model,the modeled S parameters based on the proposed model considering DC/AC dispersion effect are in excellent agreement with measured S parameters.The accuracy is within 6%.4)An emitter-length scalable noise and small-signal model for HBT devices are proposed.A set of scalable expressions for noise and small-signal model parameters are derived.The proposed model is verified by InP HBT devices in the frequency ranges of 2-20 GHz.A noise equivalent circuit model with individual un-correlated noise sources is proposed.By introducing the collector current factor to replace the correlation coefficient between the base and collector noise sources.The base noise source and the collector noise source are independent and uncorrelated,which solves the problem that the conventional model can not be easily incorporated into the simulation software since the noise sources are not independent.The proposed model is verified by InP and Ga As HBT devices.The results show that good agreement can be obtained between the measured data and the modeled data.The proposed scalable model can predict RF and noise performance of HBT devices with different physical sizes.The noise equivalent circuit model with individual un-correlated noise sources can be well adapted to commercial circuit simulation software.In conclusion,the behavior and characterization methods of ?-? compound-based HBT devices have been systematically investigated in this thesis.After device tape-out testing and compared with the simulated results,the effectiveness of the proposed modeling techniques and parameter extraction methods have been verified.