基于Hammerstein模型的模拟电路结构级行为模型建模方法研究

 本文提出了一种适用于较大规模模拟电路行为级的建模方法.首先,将任何一个模拟电路等效为由电源(Source)、放大器(Amplifier,也可以看作为一个有增益的滤波器)、开关(Switch)、阻抗(Impedance)、等基本单元组成的网络.本文把这种网络称为模拟电路的SASI结构.其次,根据此种划分下的网络结构和Hammerstein模型结构的等价性,基于Hammerstein模型对模拟电路的宏模块进行建模.最后,采用硬件描述语言(Verilog-A,VHDL-AMS等)来描述这种SASI结构,从而完成整个模拟电路的行为级建模.采用该方法建立的模拟电路行为模型是一个参数化非线性动态模型,有利于模拟电路系统级整体设计.以采用"Top-Down"法设计红外遥控接收器、建立其行为模型为例,结果表明了该建模方法的有效性.     

非线性直流增益对Delta-Sigmal开关电容调制器的影响

现有的Delta-Sigmal开关电容调制器模型中,没有考虑积分器的有限直流增益(DCG)非线性因素.通过对非线性DCG分析、估算,给出它的分析、估算与模型.同时给出一套精确的开关电容Δ∑调制器的行为级模型.该模型同时考虑了噪声(开关与运放的热噪声)、时钟抖动,以及非理想情况下,积分器与运放的有限直流增益与单位增益带宽等因素.通过对二阶调制器行为级模型的仿真,验证了非线性有限直流增益会使调制器的输出谐波失真、背景噪声急剧增加,加剧了调制器在行为级上的不可预测性.     

基于SIMULINK的开关型∑-△调制器行为级建模

为精确反映多种非理想因素对开关型∑-△调制器的影响,提高其在SIMULINK仿真器下的仿真精度,针对SIMULINK的行为级建模提出一种新的积分器模型.主要的改进之处包括:在运放模块中引入了有关直流增益非线性及信号建立过程非理想性的考虑,在开关模块中引入了电荷注入效应和导通阻抗的信号相关性影响,并将噪声模型作为独立模块引入系统.应用该模型进行SIMULINK仿真,并与TSMC 0.35μm混合信号工艺下SPICE仿真结果进行比较验证.结果表明,所提出的模型成功地反映了上述因素对电路的重要影响,模型的应用提高了SIMULINK的仿真精度.     

斩波稳定型开关电容积分器的设计

利用斩波稳定技术,设计了一种用在Σ-Δ调制器中的低噪声全差分开关电容积分器,电路中的运算放大器采用套筒式共源共栅结构.详细分析了开关电容积分器中存在的非理想特性,同时讨论了斩波稳定的原理,在此基础上对积分器中的运算放大器、开关和电容进行了具体设计.经Cadence环境下的Spectre仿真验证,在3.3 V电源电压下,运算放大器的单位增益带宽为110 MHz,开环直流电压增益达76 dB,积分器在14 kHz处的等效输入噪声电压为0.2 μV·Hz-1/ 2.     

基于SIMULINK的开关型Σ-Δ调制器行为级建模

为精确反映多种非理想因素对开关型Σ-Δ调制器的影响,提高其在SIMULINK仿真器下的仿真精度,针对 SIMULINK的行为级建模提出一种新的积分器模型. 主要的改进之处包括：在运放模块中引入了有关直流增益非线性及信号建立过程非理想性的考虑,在开关模块中引入了电荷注入效应和导通阻抗的信号相关性影响,并将噪声模型作为独立模块引入系统. 应用该模型进行SIMULINK仿真,并与TSMC 0.35μm混合信号工艺下SPICE仿真结果进行比较验证.结果表明,所提出的模型成功地反映了上述因素对电路的重要影响,模型的应用提高了SIMULINK的仿真精度.     

用于高频的新颖开关电容积分器

本文研究了用于开关电容(SC)滤波器的离散积分器,所推荐的积分器是由无耗离散积分器(LDI)和双线性离散积分器的最佳线性结合而成,因此,称之为组合离散积分器(CDI)。由于这个积分器使正常转折频率增加一倍,并使高频离散积分器误差减少到最低限度,所以它对高频应用是理想的。文中给出了组合离散积分器的几种SC实现,并且还给出了以组合离散积分器为基础,模拟一般一阶和二阶的模拟滤波器单元的SC电路。     

一种引进相位裕度的∑Δ调制器行为级模型

相位裕度是影响运算放大器建立方式和建立精度的一个重要参数,在高速度高精度应用中,获得高的单位增益带宽的同时获得大的相位裕度变得非常困难。通过引入相位裕度参数提出了一种更加完整的开关电容积分器二阶瞬态响应模型,并将此模型引入到传统的ΣΔ调制器行为级模型,通过仿真分析了相位裕度对积分器建立精度以及ΣΔ调制器信噪比的影响。仿真结果表明,在其他参数相同的情况下,当相位裕度变化10°时,ΣΔ调制器的信噪比变化近5dB。     

运放的有限增益与带宽对开关电容滤波器特性的影响

本文提出了建立非理想运放等效Z模型的新方法,并以前差及后差映射积分器为例导出了非理想积分器的Z传递函数。利用这种方法,对典型的去耦式双二次二阶带通滤波器进行了计算机模拟及实验验证。所述方法可以推广应用于解决多种类型的高阶开关电容滤波器的设计问题。     

运算放大器的性能对开关电容滤波器的影响

本文以开关电容滤波器的基本组成单元──开关电容积分器为基础，较为详细地论述了CMOS运放各主要参数指标对开关电容滤波器的影响。分析结论对数字通信编译码器JSC3057的测试和研制有一定的参考价值。     

三阶级联Sigma-Delta调制器设计

介绍2-1级联的三阶调制器设计结构，讨论信号比例系数、积分增益系数和电路非理想特性对调制器系统的性能影响：运用SIMULINK对调制器建模并仿真，模型中考虑．开关电容积分器的非理想因素对整个调制器的影响．并通过调整信号比例和积分增益系数来确定调制器性能和电路要求。当采样率为125和时钟频率2．50MHz时．该模型结构得到93dB的信噪失真比，可应用于实际的电路系统。     

Applying mutual information theory to behavioural analogue fault modelling

To assess the effectiveness of a testing strategy for an integrated circuit, the potential structural faults in a circuit must be modelled. Analogue fault simulation is conventionally done at the transistor level. Behavioural fault models are desirable to speed up the simulations. Behavioural fault modelling needs faults to be grouped. However, it is not easy to group faults using a Euclidean measurement of the distance between faults, if the populations of the circuit faults have distributions with differing variances. Mutual information theory is suggested here as a robust method for clustering circuit faults. The bootstrap technique is proposed to speed up the process of generating statistical data. Statistical data on the performance of circuits under fault conditions is generated using HSPICE. A software program has been written to implement clustering of responses using mutual information theory and to generate statistical data using bootstrap. The technique is shown to generate a suitable set of parameters for a regression function. The simulation results for the behavioural models are close to those of the full circuit model. Mutual information theory is a useful technique for clustering responses of circuits under fault conditions.     

Coupled electrothermal modeling of microheaters using SPICE

In this paper,,we report a novel simulation approach that computes both the transient and steady state electrothermal behavior in integrated circuit (IC) compatible thermally isolated microheaters. The resulting distribution of heat, current density and temperature, as well as the electrical terminal behavior have been obtained for realistic device structures. The results are based on a two-dimensional solution of the coupled system of partial differential equations that govern both electrical and heat transport in the device. Unlike standard numerical approaches for coupled systems, our technique is based on the behavioural models, available in most commercial circuit simulators (e.g., HSPICE), that allow synthesis of complex, nonlinear, and coupled circuit elements. The simulation results are in excellent agreement with measurement data of steady state and transient terminal characteristics, obtained under conditions of vacuum. We note that this modeling approach allows concurrent simulation (and subsequent optimization) of the performance of both the control electronics as well as the thermal element(s), within the same IC design environment     

Full-wave simulation of electromagnetic coupling effects in RF and mixed-signal ICs using a time-domain finite-element method

This paper describes the computer simulation and modeling of distributed electromagnetic coupling effects in analog and mixed-signal integrated circuits. Distributed electromagnetic coupling effects include magnetic coupling of adjacent interconnects and/or planar spiral inductors, substrate coupling due to stray electric currents in a conductive substrate, and full-wave electromagnetic radiation. These coupling mechanisms are inclusively simulated by solving the full-wave Maxwell's equations using a three-dimensional (3-D) time-domain finite-element method. This simulation approach is quite general and can be used for circuit layouts that include isolation wells, guard rings, and 3-D metallic structures. A state-variable behavioral modeling procedure is used to construct simple linear models that mimic the distributed electromagnetic effects. These state-variable models can easily be incorporated into a VHDL-AMS simulation providing a means to include distributed electromagnetic effects into a circuit simulation.     

Pspice resonant tunneling diode models and application circuits

Using the analogue behavioural modelling capabilities of Pspice, the current–voltage characteristics and the large-signal equivalent circuit of a resonant tunneling diode are exploited to create a Pspice compatible model for the diode. The model is used, with very few other components, in the simulation of a number of circuit applications, including a sinusoidal wave generator, a frequency multiplier and three state logic circuits. The simulated circuit details, the related waveforms and three-state logic operations are described. The circuits are characterized mainly by their reduced complexity and ease of analysis.     

Designing SRCOs by combining SPICE and Verilog-A

The design of single-resistance-controlled oscillators (SRCOs) is presented by using current followers (CF) and voltage followers (VF). First, the design of the followers is described by using SPICE and standard CMOS technology of 0.35?µm. Second, a SRCO is simulated in SPICE by using the designed CF and VF. Third, the SRCO is simulated in Verilog-A by using ideal and real behavioural models for the followers. Finally, the good agreement on the simulation results leads us to conclude on the usefulness to combine SPICE and Verilog-A to enhance analogue integrated circuit design.     

A MESFET Model for Use in the Design of GaAs Integrated Circuits

A MESFET model is presented that is suitable for use in conventional, time-domain circuit simulation programs. The parameters of the model are evaluated either from experimental data or from more detailed device analysis. The model is shown to be more complete than earlier models, which neglect transit-time and other effects. An integrated circuit (IC) design example is discussed.     

Direct tunnelling models for circuit simulation

This paper presents a review of models for direct tunnelling with a view to identifying suitable models for inclusion in a circuit simulator. For thin oxides, the critical quantities required for the derivation of tunnel current are the transparency of the barrier, the oxide field and the supply of carriers for tunnelling. This paper reviews different approaches to the incorporation of these quantities in analytical models. A new model for direct tunnelling, which includes quantum effects in a format suitable for circuit simulation, is outlined. Recent developments in MOSFET models, which include gate current, are briefly discussed.