PIN光探测器的小信号电路模型参数的提取

提出了一种利用自适应遗传算法提取p-i-n光探测器小信号电路模型参数的方法.文章首先根据p-i-n光探测器的物理结构确定其等效电路模型,进而采用自适应遗传算法对测量的S参数进行拟合,提取模型参数.自适应遗传算法自动优化交叉概率和变异概率,避免了以往遗传算法中易早熟的缺点.利用该法成功提取出模型的10个参数,建立光探测器小信号电路模型.在130 MHz～20 GHz范围内的实验结果表明,模型仿真结果和测量结果相吻合,证明了这种参数提取方法的可靠性.     

Broad-band determination of the FET small-signal equivalent circuit

A method to determine the broadband small-signal equivalent circuit of field-effect transistors (FETs) is proposed. This method is based on an analytic solution of the equations for the Y parameters of the intrinsic device and allows direct determination of the circuit elements at any specific frequency or averaged over a frequency range. The validity of the equivalent circuit can be verified by showing the frequency independence of each element. The method can be used for the whole range of measurement frequencies and can be applied to devices exhibiting severe low-frequency effects     

A table-based bias and temperature-dependent small-signal and noiseequivalent circuit model

A new algorithm is presented for construction of accurate table-based bias and temperature dependent field-effect transistor (FET) small-signal and noise models. The algorithm performs two-dimensional (2-D) linear interpolation on a single stored data table to quickly produce bias and temperature-dependent model simulations. Comparisons of simulated FET S-parameters, noise figure, and device figures of merit (e.g., G_max) versus measured data show the model to be accurate over a wide range of bias and temperatures. Model enabled simulations of a single-stage FET-based low-noise monolithic microwave integrated circuit (MMIC) amplifier are also shown to compare favorably with measured amplifier data. The new algorithm improves on previously available approaches in three ways: (1) it allows efficient and accurate small signal device and circuit simulations over bias and temperature; (2) it allows circuit optimization with respect to bias and temperature; and (3) it provides substantial data storage reduction over alternate approaches. Because one compact data table represents a single sample device, the approach can be readily adapted for use in a statistical FET model data base     

自适应开启时间Buck变换器定时器电路设计

设计了一种用于自适应开启时间(adaptive on-time,AOT)Buck型DC-DC变换器的定时器电路,采用了输入电压前馈补偿和输出反馈技术,使开关频率不随输入、输出电压变化,实现了固定频率的伪脉冲宽度调制。基于0.18μm BCD工艺进行电路设计,并使用Hspice仿真验证。仿真结果表明当输入电压从5~18 V,相同输出电压下开关频率变化不超过10 k Hz,不同的输出电压下系统开关频率变化不超过20 k Hz。同时,由于定时器中采用输入电压前馈技术,提高了输入线性瞬态响应速度。     

Very high-frequency small-signal equivalent circuit for shortgate-length InP HEMTs

A small-signal equivalent circuit for short gate-length InP high electron-mobility transistors (HEMTs) operating at very high frequency (HF) is proposed. First, the extrinsic parameters of the equivalent circuit are determined using a cold HEMT, but without forward gate bias. Then the intrinsic parameters of the equivalent circuit are extracted, including the frequency dependence of some of them. A fast and accurate method based on least-squares regressions is presented to obtain the extrinsic and intrinsic parameters from measured S-parameters. The improved equivalent circuit accurately fits the S-parameters of 0.25-μm InP HEMTs over the 500-MHz up to 40-GHz measurement bandwidth, for all gate-to-source and drain-to-source voltages     

含受控源电路的分析与等效计算

从线性电路中任两个支路的电压或电流之间存在一次函数的角度出发,系统地分析了受控源所表现的电路性质,给出了受控源的等效计算方法。     

A small-signal linear equivalent circuit of HEMTs fabricated onGaAs-on-Si wafers

A new small-signal linear equivalent circuit for high electron mobility transistors (HEMTs) fabricated on GaAs-on-Si wafers, HEMTs-on-Si, has been proposed. The new equivalent circuit describes the microwave characteristics of HEMTs-on-Si much better than the conventional metal-semiconductor field-effect transistor (MESFET) equivalent circuit does. Influences of the pads, the GaAs-Si interface, and the Si substrate on the microwave characteristics are included in the circuit. It also has a great advantage in that it can separately analyze the intrinsic device characteristics and influences of Si substrate and GaAs-Si interface. Analyzes using the new equivalent circuit show that the crucial problem of HEMTs-on-Si is the larger values of the pad capacitances and the drain-source capacitances than those of HEMTs fabricated on GaAs bulk wafers, HEMTs-on-GaAs, and that the substrate resistivity is not an important factor for microwave performances of HEMTs-on-Si. The microwave performance was improved by the reduction of the pad capacitances     

A peeling algorithm for extraction of the HBT small-signal equivalent circuit

Direct extraction is the most accurate method for the determination of equivalent-circuits of heterojunction bipolar transistors (HBTs). The method is based on first determining the parasitic elements and then the intrinsic elements analytically. The accuracy and robustness of the whole algorithm therefore is determined by the quality of the extraction of the extrinsic elements. This paper focuses on a new extraction method for the extrinsic capacitances which have proven to be the main source of uncertainty compared to the other extrinsic parameters. Concerning the intrinsic parameters, all the elements are extracted using exact closed-form equations, including exact expressions for the base-collector capacitances, which model the distributed nature of the base. The expressions for the base-collector capacitances are valid for both the hybrid-/spl pi/ and the physics-based T-topology equivalent circuits. Extraction results for InP HBT devices on measured S-parameters up to 100 GHz demonstrate good modeling accuracy.     

热电制冷器的等效电路模拟与分析

作为半导体激光器组件的重要一部分，热电制冷器（TEC）工作特性的模拟对激光器组件的设计与优化有着重要的意义。根据实际器件的结构模型，建立了考虑各种影响因素所造成的附加热阻和接触电阻的数学模型，进而推导出TEC的等效电路模型。用SPICE进行了TEC各种特性的仿真和讨论，分析了环境温度、制冷功率、附加热阻、接触电阻、工作电流以及电流源等对TEC工作特性的影响。采用等效电路模拟对于TEC的设计、优化和应用控制是一种有效的方法。     

Normal-mode small-signal analysis of traveling-wave directionalcouplers

The small-signal frequency responses of the 1×2 and 2×2 directional coupler traveling-wave modulators are analyzed in closed forms including the effect of both the optical/microwave velocity mismatch and microwave loss. When the microwave loss is negligible, the small-signal bandwidths of 1×2 and 2×2 directional coupler traveling-wave modulators are 20 and 28%, respectively, larger than that of an interferometric modulator with the same electrode length. However, when the microwave loss is large, the 1×2 coupler has a larger bandwidth     

A physically based small-signal circuit model for heterostructureacoustic charge transport devices

A physically based small-signal circuit model for GaAs-AlGaAs Schottky gate heterostructure acoustic charge transport (HACT) devices is presented. Analytical expressions for the instantaneous and average channel current as a function of gate voltage are obtained from physical device parameters. The charge injection model is based on subthreshold current models for GaAs MESFETs. It is shown that the shape of the sampling aperture of the charge injection operation is approximately Gaussian. Good agreement is obtained between the measured DC channel current versus gate voltage and that predicted by the model. Equivalent circuits for the transfer and output sensing operations and expressions for noise sources due to the physical processes that occur within the device are developed. Thermal, shot, and transfer noise are treated. The form of the analytic expressions for frequency response and noise figure allows easy implementation on commercially available CAE software. Simulations of both gain and noise figure performed on Libra show good agreement with measured data     

Direct extraction of the AlGaAs/GaAs heterojunction bipolartransistor small-signal equivalent circuit

The authors describe a novel, direct technique for determining the small-signal equivalent circuit of a heterojunction bipolar transistor (HBT). The parasitic elements are largely determined from measurements of test structures, reducing the number of elements determined from measurements of the transistor. The intrinsic circuit elements are evaluated from y-parameter data, which are DC-embedded from the known parasitics. The equivalent-circuit elements are uniquely determined at any frequency. The validity of this technique is confirmed by showing the frequency independence of the extracted circuit elements. The equivalent circuit models the HBT s-parameters over a wide range of collector currents. Throughout the entire 1-18-GHz frequency range, the computed s-parameters agree very well with the experimental data     

Generalized small-signal analysis of avalanche transit-time diodes

The one-dimensional small-signal analysis of avalanche transit-time diodes with distributed multiplication is reduced to the concept of two layers in cascade, each having a constant ionization rate. The interface is located in the distinguished neutral plane of equal direct electron and hole currents. In this configuration the small-signal problem is characterized by two parameters : namely the location of the neutral plane in the depletion layer and a quantity combining the ionization-rate field dependence and the total direct current density. Normalized admittance diagrams and small-signal growth rates are given which show the relative importance of the low-transit-angle mode where the frequency is smaller than the avalanche resonance frequency and the π mode extending almost to 2π for large current densities. Through a transformation the results are applicable to Read type, abrupt and uniform junctions of Si, Ge, and GaAs avalanche diodes.     

A novel small-signal equivalent circuit model for GaN HEMTs incorporating a dual-field-plate

An accurate and novel small-signal equivalent circuit model for GaN high-electron-mobility transistors (HEMTs) is proposed, which considers a dual-field-plate (FP) made up of a gate-FP and a source-FP. The equivalent circuit of the overall model is composed of parasitic elements, intrinsic transistors, gate-FP, and source-FP networks. The equivalent circuit of the gate-FP is identical to that of the intrinsic transistor. In order to simplify the complexity of the model, a series combination of a resistor and a capacitor is employed to represent the source-FP. The analytical extraction procedure of the model parameters is presented based on the proposed equivalent circuit. The verification is carried out on a 4 × 250 μm GaN HEMT device with a gate-FP and a source-FP in a 0.45 μm technology. Compared with the classic model, the proposed novel small-signal model shows closer agreement with measured S-parameters in the range of 1.0 to 18.0 GHz.     

Coupled-wave small-signal transient analysis of GaAs distributedamplifier

The analysis takes into consideration the effect of c_dg in the active device, leading to a coupled-mode formulation. Dispersions within the transmission lines and the presence of two normal modes make it impractical to obtain broadband matching. Numerical results for specific terminations and various degrees of passive and active coupling clearly indicate the influence of c _dg and the necessity for coupled-mode analysis. The numerical scheme, which is based on Bromwich integration, can be incorporated into CAD routines for time-domain response optimization     

超微晶合金磁特性测量高频小信号放大电路设计

在超微晶合金样片二维高频旋转磁特性测试时,针对B-H复合型磁滞矢量传感器中传感信号微弱且易受到周围电磁环境的干扰而产生很大的噪声的问题,设计一种以高性能仪表放大器AD8221作为主要器件的差分放大器和高通滤波器、低通滤波器、直流偏置调节电路等组成的高频小信号放大电路。并将该硬件电路应用在H线圈的校准实验中,确定了H线圈的校准系数。     

基于PIC16F877A的小信号采集电路设计

在感应测井中,所接收到的信号本身会很小,受到噪声的干扰非常明显。因此,本文设计出了一种基于单片机的小信号采集电路,首先通过滤波电路,并从中提取出有用信号,然后再对信号进行放大,之后再通过采用PIC单片机为主控芯片来控制16位的A/D974对信号进行采集、编码处理,从而便于后续电路的处理。本文详细描述了硬件电路的设计,以及通过单片机软件编程与电路相配合,从而实现了小信号的采集过程,并且经过多次实验,验证了电路的稳定性、可靠性。     

Techniques for small-signal analysis of semiconductor devices

Techniques for ascertaining the small-signal behavior of semiconductor devices in the context of numerical device simulation are discussed. Three standard approaches to this problem will be compared: (i) transient excitation followed by Fourier decomposition, (ii) incremental charge partitioning, and (iii) sinusoidal steady-state analysis. Sinusoidal steady-state analysis is shown to be the superior approach by providing accurate, rigorously correct results with reasonable computational cost and programming commitment.     

Modeling of small-signal minority-carrier transport in bipolardevices at arbitrary injection levels

A detailed analytical treatment of small-signal minority-carrier transport in quasi-neutral regions with position-dependent material parameters at arbitrary injection levels is presented. First, the small-signal minority-carrier transport equations are derived in a simple form which is amenable to analytical integration, thereby facilitating physical insight. Secondly, analytical solutions of the transport equations are derived by means of the integral series solution method. Next, it is shown that these solutions provide a mathematically sound basis for a systematic derivation of all nonquasi-static models hitherto presented in the literature for both the base and emitter regions of bipolar transistors. An important consequence of the above analysis is that the exact expression of all model parameters is obtained. These parameters include the conductance, transit time, charge partitioning factor and phase-shift factor. The dependence of these parameter on the most significant technological parameters and on the operating point is analyzed in detail