Sigrity SPEED2000 Power Ground Noise Simulation模式如何進(jìn)行電源阻抗仿真分析操作指導(dǎo)(一)-無電容

Sigrity Power Ground Noise Simulation模式同樣可以用來觀測電源網(wǎng)絡(luò)的自阻抗，以下圖為例進(jìn)行說明

2D 視圖

3D view

本例要觀測的是U17端口處的自阻抗，通過觀測電壓和電流的時域波形然后計算得出

具體操作如下

1. 首先切換到Power Ground Noise Simulation模式

1. 點擊Check Stackup ，確保層疊信息無誤，點擊ok

1. 點擊Prepare Power Ground Nets，選擇Skip setup P/G nets,跳過設(shè)置電源地

1. 自動跳轉(zhuǎn)到Net Manager界面，使能VCC和GND以及D2-D4信號網(wǎng)絡(luò)

1. 點擊Assign Capacitor Models，設(shè)置電容模型

由于本例中電容不參與仿真，所以跳過這步

1. 點擊Add Excitation，設(shè)置激勵

1. 跳轉(zhuǎn)到Component Manager界面，選中Vsource，點擊edit

1. 彈出Edit Model界面

1. 在definition中定義激勵源參數(shù)，為高斯波形

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

Rs? 2? 1?? 2

高斯波形參數(shù)說明如下，本例中將電流換成電壓

1. 點擊ok關(guān)閉頁面

1. 將Redge定義為終端電阻，電阻為0.01ohm

1. 回到workflow，點擊Setup VRAM&Decaps，設(shè)置VRAM和電容，本例中不需要設(shè)置，直接跳過

1. 點擊Specify Sim Time&Options,設(shè)置仿真時長為20ns，點擊ok

1. 點擊Specify Observations(Voltage)，設(shè)置電壓觀測點，本例設(shè)置電壓觀測點為Vsource

1. 點擊Specify Observations(Current)，設(shè)置電流觀測點，點擊Vsource的Rs，點擊add，添加好電流觀測點

1. 點擊Auto Mesh size，進(jìn)行自動網(wǎng)格設(shè)置

1. 點擊error Check and Warning ，檢查錯誤和警告

1. 點擊Save，保存文件

1. 彈出界面，點擊ok

1. 點擊Start Simulation開始仿真

1. 點擊ok

1. 仿真結(jié)束后，點擊Window選擇2D Curves，查看2D曲線

1. 可以看到Vsource端的電壓和電流時域曲線

1. 接下來通過公式計算阻抗頻域曲線，在time domain下拉選擇Amplitude

1. 視圖切換到電壓和電流的頻域曲線

1. 在結(jié)果界面空白處鼠標(biāo)右擊選擇FD Calculate，進(jìn)行頻域計算

1. 彈出Fourier Calculator，進(jìn)行傅里葉變換

1. 切換到Simple Calculation，最左邊選擇V1，中間選擇/(表示除以)，最右邊選擇C1，然后點擊ok

1. 得到vsource端的自阻抗曲線，可以看到在0hz的時候，諧振幅度較大

1. 當(dāng)然不僅僅是0hz的幅度很大，在更高頻段也很大，只是相比0hz幅度視圖看起來不明顯，如680Mhz，幅度也達(dá)到了63.5262

1. 選中曲線，鼠標(biāo)右擊選擇Save

1. 命名成curve-no decap，點擊保存，便于后續(xù)結(jié)果的比較

1. 除了可以計算阻抗曲線外，還可以計算電源地的有效電感

1. 結(jié)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?