基于CQFP 64线外壳的封装寄生参数研究

封装寄生效应对高频器件性能的影响越来越明显.为了在高频器件设计中充分考虑寄生参数的影响,需对封装的寄生效应进行模拟,以便保持高频电路封装后信号的完整性.利用Anfost公司的软件Q3D和HFSS,对CQFP 64管壳的引脚和键合线进行电磁仿真分析,提取出三维封装结构的RLC参数和高频下的S参数;分析管壳在封装前后、不同频率、不同封装环境下寄生参数的变化情况;将仿真结果与实验结果进行了对比,为设计人员设计产品提供依据.     

基于小信号等效电路模型的HBT本征稳定性研究

本文基于小信号等效电路模型,对异质结双极晶体管的本征稳定性进行了分析和讨论。稳定性因子（即K因子）用于评估器件的高频稳定特性。基于HBT的T型等效电路模型,推导了K因子的理论分析公式,并全面分析了小信号模型中物理参数对器件本征稳定性的影响,得到了提高器件本征稳定性的物理参数优化设计方法。测试计算了多个不同物理参数的HBT样品的稳定性因子K。物理参数对器件稳定性影响的实验结果与理论分析的影响规律一致。     

Si/SiGe异质结晶体管的参数提取与特性模拟

用实验测量和理论计算相结合的方法提取了Si/SiGe异质结晶体管的直流和高频参数,分别在PSPICE和MATLAB软件平台上模拟并分析了器件的直流和高频特性,模拟结果与实际测量的结果相吻合,表明本文的提取方法可行、参数提取结果有效.     

应用于WLAN的SiGe HBT高频功率特性的优化

高频大功率HBT作为无线和射频通信PA中的重要器件,其设计和制作也越来越受到关注.高频大功率SiGe HBT的设计目的是在一定的工作频率下维持一个高的击穿电压和大的电流密度以实现大的输出功率.器件的设计参数需要进行折中优化.文中模拟计算了两个单元叉指结构的SiGe HBT的高频特性和在5GHz工作频率下的功率特性与发射区掺杂浓度、厚度、基区Ge组分大小以及收集区的掺杂特性等参数之间的关系,并对模拟结果进行了分析和探讨.给出了一些具有指导意义的结论,为高频大功率HBT的设计提供了很好的参考.     

应用于WLAN的SiGe HBT高频功率特性的优化

高频大功率HBT作为无线和射频通信PA中的重要器件,其设计和制作也越来越受到关注.高频大功率SiGe HBT的设计目的是在一定的工作频率下维持一个高的击穿电压和大的电流密度以实现大的输出功率.器件的设计参数需要进行折中优化.文中模拟计算了两个单元叉指结构的SiGe HBT的高频特性和在5GHz工作频率下的功率特性与发射区掺杂浓度、厚度、基区Ge组分大小以及收集区的掺杂特性等参数之间的关系,并对模拟结果进行了分析和探讨.给出了一些具有指导意义的结论,为高频大功率HBT的设计提供了很好的参考.     

GaAs MESFET特性的计算机模拟

为了定量地分析GaAsMESFET的物理参数和几何参数对其电性能的影响,本论文计算了GaAsMESFET的直流Ⅰ-ⅴ特性、等效电路参数及高频性能。本论文从GaAs电子速度-电场的两段线性近似出发,考虑了栅下耗尽层向漏端及源端的延伸,通过编制计算机程序求解GaAsMESFET的沟道电流-电压方程,得到了器件等效电路参数和高频参数与器件几何参数和材料参数以及偏压的关系。作为实例,本文计算了栅长1μm左右、栅宽1.2mm的GaAs功率器件DX52的直流Ⅰ-Ⅴ特性和高频性能,与测试结果符合较好,这些计算方法能够用来作为器件设计的依据。     

射频场效应晶体管的交流小信号建模技术研究

提出了新的金属-氧化层-半导体-场效晶体管（MOSFET）器件的小信号等效电路结构,提取了等效电路结构的元件参数值,在器件建模型软件IC-CAP2008下,对等效电路模型和提取的元件参数进行编译,生成了能够应用于射频与微波领域的场效应晶体管的高频小信号器件模型,将生成的器件模型编译到高频仿真软件ADS中,并调用S参数仿真器对器件模型进行S参数仿真,最后对比了仿真结果与测试数据的差异性,对生成的器件模型做出了误差分析,展示了所建小信号模型的良好性能。     

高阻Si衬底对SiGe HBT高频性能的改善研究

选用电阻率高达1 000Ω·cm的硅衬底结构改善SiGe HBTs频率性能。介绍了器件的结构设计,根据衬底寄生参数模型分析了衬底阻抗影响器件高频性能的原理,计算出器件f_T和f_(max)随衬底电阻率变化的规律。测试结果表明,高电阻率衬底器件比n~+衬底器件的特征频率f_T提高了28%,而最高振荡频率f_(max)提高了47.7%;表明高电阻率衬底基本消除了SiGe HBT中大多数容性寄生网络;通过对器件的最小噪声系数的计算与测试分析,发现高阻Si衬底的引入使器件的噪声系数在低频时几乎不变,在高频时轻微增加。     

光探测器芯片小信号等效电路模型的建立

提出了一种光探测器芯片小信号等效电路模型及其建立方法.首先根据光探测器的物理结构确定其等效电路模型,模型考虑了影响光探测器高频性能的主要因素.然后精确测量了光探测器芯片的S参数,通过遗传算法对测量的S参数进行拟合,最终计算出模型的各个参量.在130MHz～20GHz范围内的实验结果表明,模型仿真结果与测量结果相吻合,证明了建模方法的可靠性.该模型有效地模拟了光探测器芯片的高频特性,利用该模型可以对光探测器及相应光电集成器件进行电路级仿真和优化.     

Ge组分对SiGe HBT主要电学特性的影响

采用SiGe异质结结构提高晶体管的性能,分析了Ge对器件电流增益和频率特性提高的物理机制.综合考虑了Si1-xGex薄膜的稳定性、工艺特点和器件结构对Ge含量以及分布的要求和Ge组分的设计及其对器件电学特性的影响.从理论上推算了SiGe HBT的β和fT等主要特性参数,Ge的引入以及Ge的分布情况对提高这些参数有着显著的影响.Ge的引入对晶体管主要特性参数的提高使得SiGe HBT技术在微波射频等高频电子领域可以有更重要的应用前景.     

Extraction of high-frequency equivalent circuit parameters ofsubmicron gate-length MOSFET's

As the effective gate-length of a MOSFET reduces, its high-frequency characteristics improve. However, they become more difficult to model. Current SPICE models are based on DC measurement data and simplistic capacitance models which can only approximate the high-frequency device characteristics up to a fraction of the device unity current gain frequency (f_τ). Thus, it is important to investigate the high-frequency characteristics and then incorporate the small-signal equivalent circuit parameters in SPICE. In this, work we report a simple nonquasi static model, which offers good accuracy needed for circuit simulation, and a new curve fitting method for the extraction of the network model elements. The current work is part of a study aimed at improving the existing scalable model for MOSFET's, and it focuses on extracting the elements of an equivalent circuit which describes the state-of-the-art device     

Power and stability limitations of resonant tunneling diodes

Stability criteria for resonant tunneling diodes are investigated. Details of how extrinsic elements, such as series inductance and parallel capacitance, affect the stability are presented. A GaAs/AlAs/InGaAs/AlAs/GaAs double-barrier diode is investigated, showing the effect of different modes of low-frequency oscillation and the extrinsic circuit required for stabilization. The effect of device stabilization on high-frequency power generation is described. The main conclusions of the paper are: (1) stable resonant tunneling diode operation is difficult to obtain, and (2) the circuit and device conditions required for stable operation greatly reduce the amount of power that can be produced by these devices     

Linear operation of a p-n-p-n tetrode

At the present time all p-n-p-n devices are used exclusively as switches. The p-n-p-n tetrode however, is also capable of operating as a linear amplifier. A model describing the operation of such a device as a semiconductor tetrode amplifier is presented. The equations characterizing this model are based on the physical structure of a commercially available silicon planar p-n-p-n tetrode; they are used 1) to derive the device terminal characteristics, 2) to synthesize small-signal equivalent circuits suitable for low-frequency operation (h-parameter circuit) and for high-frequency operation (bridged hybrid-π circuit), 3) to study the dependence of short-circuit gains of the tetrode on the dc biasing currents and frequency, and 4) to obtain a stability condition which must be satisfied to insure that the operation of the device is restricted in its OFF state where it can function as a small-signal linear amplifier. The theoretical results are in close agreement with experimental values.     

Experimental equivalent-circuit modeling of SMD inductors forprinted circuit applications

An understanding of the high-frequency parasitic and packaging effects of passive surface-mounted devices (SMDs) can be gained from equivalent-circuit characterization of the device. We develop a circuit model which accurately characterizes the nonideal behavior of SMD inductors mounted on a printed circuit board (PCB), considering the device packaging and the interaction between board layout and component parasitics. The model is valid over a wide frequency band up to the first resonance of the inductor. The equivalent-circuit parameters are extracted in closed form from an accurate measurement of the S-parameters of the board-mounted SMD inductor, without the necessity for cumbersome optimization procedures normally followed in RF circuit synthesis. This procedure of measuring the component in its designed PCB environment is referred to as extrinsic characterization, in contrast to the conventional intrinsic characterization employed in RF bridges and LCR meters, which does not include the board layout effects. The developed closed-form model can be directly incorporated in commercial CAD packages, and thus, it simplifies the analysis of electromagnetic field behavior in PCBs, such as prediction of radiated emissions, signal integrity, and EMI     

Broadband Modeling of High-Frequency Microwave Devices

Circuit modeling of high-frequency devices described by tabulated multiport parameters has generated immense interest during recent years. In most cases, equivalent circuit models (ECMs) are available to the designers, which correlate well with the measured parameters at lower frequencies, however, deviate at higher frequencies. Traditional efforts to improve ECMs are device specific, laborious, and ad-hoc in nature. In order to address these difficulties, this paper presents an efficient and automated algorithm to identify appropriate frequency-dependent elements for adding to the ECM at arbitrary locations so as to correct for high-frequency errors. The new method enables the designers to retain their existing physical models while providing a means to capture the high-frequency effects accurately.      

Electrical and Optical Coupling in an Electroabsorption Modulator Integrated With a DFB Laser

Electrical and optical coupling in an electroabsorption (EA) modulator integrated with a distributed feedback (DFB) laser have been investigated. The integrated device is treated as a three-port optoelectronic device with two electrical ports and one optical output port. The scattering parameters of this three-port device have been measured in the designed experiment. The measured results indicate that there exists the electrical coupling between the DFB laser and EA modulator of the integrated light source whenever the current applied to the laser section is below or above the threshold current, and the optical coupling will have stronger influence on the frequency responses than the electrical coupling when the bias current is above the threshold. A small-signal equivalent circuit model for the integrated device is established considering both the electrical and internal optical coupling. Experiments show that the equivalent circuit model is reasonable and the determined element values are correct. Based on the measurement and modeling, the influences of the electrical and optical coupling on the high-frequency responses are investigated and the effective measure to eliminate the additional modulation in the DFB laser are discussed.     

A circuit simulation model for high-frequency power MOSFETs

A circuit simulation model suitable for modeling the static and dynamic switching characteristics of high-frequency power MOSFETs is reported. The model parameters were obtained from physical device layout, silicon doping, and measured electrical characteristics of power MOSFETs. Accurate voltage dependencies of the interelectrode capacitances were obtained from extensive two-dimensional device simulations. The voltage dependence of gate-drain capacitance was modeled using an analytic expression. The measured static current-voltage and transient-switching responses under resistive switching conditions are in excellent agreement with simulation results obtained from SPICE. The MOSFET subcircuit model was used to accurately predict the performance of a series-parallel resonant DC-DC converter using a multilevel system simulator     

一种基于数值模型的4H-SiC MESFET大信号建模方法

提出了一种基于数值模型的4H-SiC MESFET大信号建模方法.该方法基于4H-SiC MESFET的物理参数和结构参数,采用MEDICI的小信号正弦稳态分析法和高频小信号等效电路,模拟得到电流和电容的非线性特性,通过大信号等效电路,分析了建立4H-SiC MESFET大信号模型的途径.模拟与实验测试值的比较表明这种方法是可行的,可用于预先评估器件大信号工作时的非线性特性,指导4H-SiC MESFET的器件设计.     

High-frequency heterojunction bipolar transistor device design andtechnology

This paper identifies and reviews those aspects of new materials and device technological advances that have pushed HBT circuits towards a 100 GHz operating frequency. The operating principles of the HBT are initially discussed in relation to their differences from homojunction bipolar transistors. The advantages and disadvantages of the various materials systems available to HBTs, how the particular material properties relate to the device performance and a brief outline of growth technologies are then presented. Those device parameters contributing to the frequency performance figures-of-merit are identified and the resulting design approaches discussed. Current device fabrication technology is then reviewed, with the latest results and the most important design aspects for high-frequency operation identified. This is then followed by examples of achievements in both digital and analogue circuit applications. Finally, an attempt is made to identify those device and materials aspects that are likely to contribute to a further improvement in the frequency performance of HBTs     

Stability of high-frequency transistor in common-emitter configuration

This letter describes the stability of the common-emitter transistor in terms of the y parameters in the high-frequency range; the graphical representation of the normalised input admittance of the transistor is also shown. This representation is useful and convenient for investigating performance of the input admittance in both design and analysis of circuits. The maximum frequency of potential instability of the common-emitter transistor is established using an approximate high-frequency equivalent circuit of a junction transistor.