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Sigrity SPEED2000 Power Ground Noise Simulation模式如何进行电源阻抗仿真分析操作指导(一)-无电容

Sigrity Power Ground Noise Simulation模式同样可以用来观测电源网络的自阻抗，以下图为例进行说明

2D 视图

3D view

本例要观测的是U17端口处的自阻抗，通过观测电压和电流的时域波形然后计算得出

具体操作如下

1. 首先切换到Power Ground Noise Simulation模式

1. 点击Check Stackup ，确保层叠信息无误，点击ok

1. 点击Prepare Power Ground Nets，选择Skip setup P/G nets,跳过设置电源地

1. 自动跳转到Net Manager界面，使能VCC和GND以及D2-D4信号网络

1. 点击Assign Capacitor Models，设置电容模型

由于本例中电容不参与仿真，所以跳过这步

1. 点击Add Excitation，设置激励

1. 跳转到Component Manager界面，选中Vsource，点击edit

1. 弹出Edit Model界面

1. 在definition中定义激励源参数，为高斯波形

Vs  2  0   Gaussian(0  1  1.0n  0.7n  1)

Rs  2  1   2

高斯波形参数说明如下，本例中将电流换成电压

1. 点击ok关闭页面

1. 将Redge定义为终端电阻，电阻为0.01ohm

1. 回到workflow，点击Setup VRAM&Decaps，设置VRAM和电容，本例中不需要设置，直接跳过

1. 点击Specify Sim Time&Options,设置仿真时长为20ns，点击ok

1. 点击Specify Observations(Voltage)，设置电压观测点，本例设置电压观测点为Vsource

1. 点击Specify Observations(Current)，设置电流观测点，点击Vsource的Rs，点击add，添加好电流观测点

1. 点击Auto Mesh size，进行自动网格设置

1. 点击error Check and Warning ，检查错误和警告

1. 点击Save，保存文件

1. 弹出界面，点击ok

1. 点击Start Simulation开始仿真

1. 点击ok

1. 仿真结束后，点击Window选择2D Curves，查看2D曲线

1. 可以看到Vsource端的电压和电流时域曲线

1. 接下来通过公式计算阻抗频域曲线，在time domain下拉选择Amplitude

1. 视图切换到电压和电流的频域曲线

1. 在结果界面空白处鼠标右击选择FD Calculate，进行频域计算

1. 弹出Fourier Calculator，进行傅里叶变换

1. 切换到Simple Calculation，最左边选择V1，中间选择/(表示除以)，最右边选择C1，然后点击ok

1. 得到vsource端的自阻抗曲线，可以看到在0hz的时候，谐振幅度较大

1. 当然不仅仅是0hz的幅度很大，在更高频段也很大，只是相比0hz幅度视图看起来不明显，如680Mhz，幅度也达到了63.5262

1. 选中曲线，鼠标右击选择Save

1. 命名成curve-no decap，点击保存，便于后续结果的比较

1. 除了可以计算阻抗曲线外，还可以计算电源地的有效电感

1. 结果如下

Along with accuracy and efficiency, SPEED2000 provides an analysis flow that is particularly
valuable for design simulations that benefit from direct time domain observation. SPEED2000
can read databases from popular package and board design tools.
Chip data can also be incorporated into the same file for co-simulation. This provides an
environment for accessing the impact of noise propagation throughout the entire structure.
Circuits in the combined design are linked with SPICE circuit files.
Simulation parameters and excitation are added by the user; however, the user does not need
to create special purpose models. SPEED2000 directly provides voltage and current
waveforms.
SPEED2000 is particularly effective to be used for, but it is not limited to, the following
applications:
■ Computation of power and ground noise.
■ Determination of decoupling capacitor placement, including the number, values, and
locations of decoupling capacitors
■ Determination of frequency-dependent port parameters of packages, such as port input
impedances, S parameters, and transfer functions between different ports
■ Evaluation and design of power and ground distribution systems, including power and
ground plane arrangement, and power and ground via / pin assignment
■ Evaluation of electromagnetic coupling between different components
■ Evaluation of electromagnetic radiation from packages and printed circuit boards
■ Evaluation of signal and noise spectrum at various locations
■ Evaluation of signal and noise waveforms at various locations
■ Identification of package resonance.
SPDGEN and SPDSIM
SPEED2000 is composed of two executable modules: SPDGEN and SPDSIM.
■ SPDGEN — Provides a graphical user interface so the user can conveniently build and
modify package components and establish simulation parameters
■ SPDSIM — Provides the transient simulation engine that processes and displays the
package components. SPDSIM also provides a post processing interface so the user can
analyze, compare and print the results of package simulation
The SPDSIM simulations are entirely controlled by what the user establishes and sets up in
the SPDGEN package editor.
SPEED2000 provides powerful 3D editing functions using the SPDGEN module. Before
the.spd file (representing your package) is loaded into the SPDSIM module, the viewing and
simulation parameters need to be specified within the.spd file using the SPDGEN module.
In addition to simulation, the SPDSIM module provides a post processing interface so the
user can analyze, compare, save, export and print the results of package simulation.
■ The SPDGEN module provides the GUI-based package geometry editor and file builder,
it is used to create and edit the SPEED file (.spd) which contains package geometry and
simulation parameters
■ The SPDGEN Graphical User Interface (GUI) makes convenient “what if” analysis of a
package design possible; that is, a user can conveniently engineer a possible solution to
a problem (made apparent during the simulation) then simulate the new model to see the
results of changes made
■ The SPDSIM module loads and executes a transient simulation of the .spd file created
by SPDGEN. It should be noted that SPDSIM does not change the .spd file contents.
Use SPDGEN to select which components of a package design will be simulated