|
|
发表于 2012-3-20 13:35:55
|
|阅读模式
SPICE的全名為「特別為積體電路模擬的程式」（Simulation Program with Integrated Circuit Emphasis），是一种用于电路描述与仿真的语言与仿真器软件，用于检测电路的连接和功能的完整性，以及用于预测电路的行为。主要用于模拟电路和混合信号电路的仿真。由此我們便可以清楚地了解：SPICE這套程式原先發展的目的是為了模擬電子系統中日益重要的積體電路。
由於積體電路不如傳統電路一般。可以在麵包板（breadboard）或印刷電路板（Printed circuit board）上做實驗來驗證設計結果。
為了提高積體電路正式生產時的良率（yield）及降低成本，勢必要在進入實際製程階段前對其電路特性做「檢查」，確保性能在規格範圍之內。
發展歷史
SPICE是在1975年由加利福尼亞大學伯克莱分校的Donald Pederson在电子研究实验室首先建立的。第一版和第二版都是用Fortran语言编写的，但是从第三版开始用C语言编写。以一名為“CANCER”的電路模擬程式為藍本，發展出今日幾乎被全世界公認為電路模擬標準的SPICE原始雛型程式。
SPICE有好几种版本，成功的商业版本主要有SPECTRE（由最初的SPICE作者之一 Ken Kundert 和 Jacob White 开始最初的框架）和HSPICE（最初由MetaSoftware开发，现属于Synopsys）、Eldo（最初由Anacad公司开发，现属于Mentor Graphics）等。其后由于电路设计规模的级数级增长，旧版本的SPICE的仿真速度远远不能满足需要，并且对电路规模大小也有限制，业界发展了快速SPICE。
Silvaco公司的提供的Smartspice, SmartSpice提供最高的性能和精度，用于设计复杂的高精度模拟电路、模拟混合信号电路、分析关键网路，特性表征单元库等等。SmartSpice兼容于流行的模拟设计流程和foundry提供的器件模型。
今日在市面上所能看到的許多SPICE同類軟體：如OrCADPSpice(OrCAD)、HSPICE(Meta-Software)、IS-SPICE(intusoft)、IG-SPICE(A. B.Associates)、I-SPICE(NCSS timesharing)… 等，均是以SPICE2系列為基礎再加改進而成的商業化產品。
目前成功的快速SPICE商业版本主要有 HSIM（最初由NASSADA公司开发，现在NASSDA公司被SYNOPSYS公司购入）, NANOSIM（SYNOPSYS，但有电路规模大小的限制，对敏感的模拟电路也有精度的缺陷，在数字电路仿真方面很成功）和 ADiT（Evercad，2006年1月被Mentor Graphics并购）、ULTRASIM（CADENCE公司的快速SPICE 工具，属于最新的第三代电路仿真工具）等。目前的这些快速SPICE的主要特点是以牺牲准确性换取速度的大幅提高，因此他们的共同问题是如何在快速的同时保持准确性。
其中最廣為各級學校電子電機相關科系所使用的，就非OrCAD PSpice莫屬了。
Introduction
Unlike board-level designs composed of discrete parts, it is not practical to breadboard integrated circuits before manufacture. Further, the high costs of photolithographic masks and other manufacturing prerequisites make it essential to design the circuit to be as close to perfect as possible before the integrated circuit is first built. Simulating the circuit with SPICE is the industry-standard way to verify circuit operation at the transistor level before committing to manufacturing an integrated circuit.
Board-level circuit designs can often be breadboarded for testing. Even with a breadboard, some circuit properties may not be accurate compared to the final printed wiring board, such as parasitic resistances and capacitances. These parasitic components can often be estimated more accurately using SPICE simulation. Also, designers may want more information about the circuit than is available from a single mock-up. For instance, circuit performance is affected by component manufacturing tolerances. In these cases it is common to use SPICE to perform Monte Carlo simulations of the effect of component variations on performance, a task which is impractical using calculations by hand for a circuit of any appreciable complexity.
Circuit simulation programs, of which SPICE and derivatives are the most prominent, take a text netlist describing the circuit elements (transistors, resistors, capacitors, etc.) and their connections, and translate[3] this description into equations to be solved. The general equations produced are nonlinear differential algebraic equations which are solved using implicit integration methods, Newton's method and sparse matrix techniques.
______ Origins
SPICE was developed at the Electronics Research Laboratory of the University of California, Berkeley by Laurence Nagel with direction from his research advisor, Prof. Donald Pederson. SPICE1 was largely a derivative of the CANCER program,[4] which Nagel had worked on under Prof. Ronald Rohrer. CANCER was an acronym for "Computer Analysis of Nonlinear Circuits, Excluding Radiation," a hint to Berkeley's liberalism of 1960s: at these times many circuit simulators were developed under the United States Department of Defense contracts that required the capability to evaluate the radiation hardness of a circuit. When Nagel's original advisor, Prof. Rohrer, left Berkeley, Prof. Pederson became his advisor. Pederson insisted that CANCER, a proprietary program, be rewritten enough that restrictions could be removed and the program could be put in the public domain.[5]
SPICE1 was first presented at a conference in 1973.[1] SPICE1 was coded in FORTRAN and used nodal analysis to construct the circuit equations. Nodal analysis has limitations in representing inductors, floating voltage sources and the various forms of controlled sources. SPICE1 had relatively few circuit elements available and used a fixed-timestep transient analysis. The real popularity of SPICE started with SPICE2[2] in 1975. SPICE2, also coded in FORTRAN, was a much-improved program with more circuit elements, variable timestep transient analysis using either the trapezoidal (second order Adams-Moulton method) or the Gear integration method (also known as BDF), equation formulation via modified nodal analysis[6] (avoiding the limitations of nodal analysis), and an innovative FORTRAN-based memory allocation system developed by another graduate student, Ellis Cohen. The last FORTRAN version of SPICE was 2G.6 in 1983. SPICE3[7] was developed by Thomas Quarles (with A. Richard Newton as advisor) in 1989. It is written in C, uses the same netlist syntax, and added X Window System plotting.
As an early open source program, SPICE was widely distributed and used. Its ubiquity became such that "to SPICE a circuit" remains synonymous with circuit simulation.[8] SPICE source code was from the beginning distributed by UC Berkeley for a nominal charge (to cover the cost of magnetic tape). The license originally included distribution restrictions for countries not considered friendly to the USA, but the source code is currently covered by the BSD license.
SPICE inspired and served as a basis for many other circuit simulation programs, in academia, in industry, and in commercial products. The first commercial version of SPICE was ISPICE,[9] an interactive version on a timeshare service, National CSS. The most prominent commercial versions of SPICE include HSPICE (originally commercialized by Shawn and Kim Hailey of Meta Software, but now owned by Synopsys) and PSPICE (now owned by Cadence Design Systems). The academic spinoffs of SPICE include XSPICE, developed at Georgia Tech, which added mixed analog/digital "code models" for behavioral simulation, and Cider (previously CODECS, from UC Berkeley/Oregon State Univ.) which added semiconductor device simulation. The integrated circuit industry adopted SPICE quickly, and until commercial versions became well developed many IC design houses had proprietary versions of SPICE.[10] Today a few IC manufacturers, typically the larger companies, have groups continuing to develop SPICE-based circuit simulation programs. Among these are ADICE at Analog Devices, LTspice at Linear Technology, Mica at Freescale Semiconductor, and TISPICE at Texas Instruments. (Other companies maintain internal circuit simulators which are not directly based upon SPICE, among them PowerSpice at IBM, Titan at Infineon Technologies, Lynx at Intel Corporation, and Pstar at NXP Semiconductor.) SPICE was named an IEEE Milestone in 2011.[11]
______ Program features and structure
SPICE became popular because it contained the analyses and models needed to design integrated circuits of the time, and was robust enough and fast enough to be practical to use.[12] Precursors to SPICE often had a single purpose: The BIAS[13] program, for example, did simulation of bipolar transistor circuit operating points; the SLIC[14] program did only small-signal analyses. SPICE combined operating point solutions, transient analysis, and various small-signal analyses with the circuit elements and device models needed to successfully simulate many circuits.
______ Analyses
SPICE2 included these analyses:
AC analysis (linear small-signal frequency domain analysis)
DC analysis (nonlinear quiescent point calculation)
DC transfer curve analysis (a sequence of nonlinear operating points calculated while sweeping an input voltage or current, or a circuit parameter)
Noise analysis (a small signal analysis done using an adjoint matrix technique which sums uncorrelated noise currents at a chosen output point)
Transfer function analysis (a small-signal input/output gain and impedance calculation)
Transient analysis (time-domain large-signal solution of nonlinear differential algebraic equations)
Since SPICE is generally used to model nonlinear circuits, the small signal analyses are necessarily preceded by a quiescent point calculation at which the circuit is linearized. SPICE2 also contained code for other small-signal analyses: sensitivity analysis, pole-zero analysis, and small-signal distortion analysis. Analysis at various temperatures was done by automatically updating semiconductor model parameters for temperature, allowing the circuit to be simulated at temperature extremes.
Other circuit simulators have since added many analyses beyond those in SPICE2 to address changing industry requirements. Parametric sweeps were added to analyze circuit performance with changing manufacturing tolerances or operating conditions. Loop gain and stability calculations were added for analog circuits. Harmonic balance or time-domain steady state analyses were added for RF and switched-capacitor circuit design. However, a public-domain circuit simulator containing the modern analyses and features needed to become a successor in popularity to SPICE has not yet emerged.[12]
______ Device models
SPICE2 included many semiconductor device compact models: three levels of MOSFET model, a combined Ebers–Moll and Gummel-Poon bipolar model, a JFET model, and a model for a junction diode. In addition, it had many other elements: resistors, capacitors, inductors (including coupling), independent voltage and current sources, ideal transmission lines, and voltage and current controlled sources.
SPICE3 added more sophisticated MOSFET models, which were required due to advances in semiconductor technology. In particular, the BSIM family of models were added, which were also developed at UC Berkeley.
Commercial and industrial SPICE simulators have added many other device models as technology advanced and earlier models became inaccurate. To attempt standardization of these models so that a set of model parameters may be used in different simulators, an industry working group was formed, the Compact Model Council,[15] to choose, maintain and promote the use of standard models. The standard models today include BSIM3, BSIM4, BSIMSOI, PSP, HICUM, and MEXTRAM.
______ Input and output: Netlists, schematic capture and plotting
SPICE2 took a text netlist as input and produced line-printer listings as output, which fit with the computing environment in 1975. These listings were either columns of numbers corresponding to calculated outputs (typically voltages or currents), or line-printer character "plots". SPICE3 retained the netlist for circuit description, but allowed analyses to be controlled from a command-line interface similar to the C shell. SPICE3 also added basic X-Window plotting, as UNIX and engineering workstations became common.
Vendors and various free software projects have added schematic capture front-ends to SPICE, allowing a schematic diagram of the circuit to be drawn and the netlist to be automatically generated. Also, graphical user interfaces were added for selecting the simulations to be done and manipulating the voltage and current output vectors. In addition, very capable graphing utilities have been added to see waveforms and graphs of parametric dependencies. Several free versions of these extended programs are available, some as introductory limited packages, and some without restrictions. |
|
发表于 2012-3-20 15:42:56
|
楼主|
发表于 2012-3-20 16:11:14
|
IP卡
狗仔卡
