z*****h 发帖数: 547 | 1 如何在瞬态仿真的某个时间点仿开关电容电路的AC特性?
并且不要得到共模反馈结果后再加直流电压这类的方法
因为这会破坏求AC特性时的电路结构
而且也不适用于大批量处理(比如Monte Carlo分析)
PSS+PAC试过,但是似乎并不正确,以下面为例
switch1 A switch2
GND ___/ _________/ ____ VDD
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===
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GND
switch1和switch2是两相非交叠时钟
如果VDD的PAC幅度为1,GND是0,PSS+PAC仿真结果表明A点的幅度为1/2
但比如说我只关心switch2导通、switch1关断的某一瞬间VDD到A的增益
此时switch1电阻无穷大,switch2电阻有限
也就是相当于一个RC低通滤波器的传输函数
这个用什么仿真可以求出呢? |
z*****h 发帖数: 547 | 2 自顶一下!
【在 z*****h 的大作中提到】 : 如何在瞬态仿真的某个时间点仿开关电容电路的AC特性? : 并且不要得到共模反馈结果后再加直流电压这类的方法 : 因为这会破坏求AC特性时的电路结构 : 而且也不适用于大批量处理(比如Monte Carlo分析) : PSS+PAC试过,但是似乎并不正确,以下面为例 : switch1 A switch2 : GND ___/ _________/ ____ VDD : | : | : ===
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s**g 发帖数: 66 | 3 please clarify your question.
your schematic is confusing. |
z*****h 发帖数: 547 | 4 多谢多谢
就是问在瞬态仿真的某个时间点仿开关电容电路的AC特性?
如果有就可以直接说
下面的只是说明我用PSS+PAC仿真过,但发现结果并不是所要的,仅此而已
switch1 A switch2
GND ___/ _________/ ____ VDD
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C ===
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GND
如果GND的AC幅度=0,VDD的AC幅度=1
对于这样一个电路进行PSS+PAC仿真
那么A的AC幅度=1/2,对所有频谱均是如此
而我想要的结果是switch2导通,switch1关断的某个时间点上A的AC幅度
结果应该是1/(1+sCRon2),类似于低通滤波器传输函数
【在 s**g 的大作中提到】 : please clarify your question. : your schematic is confusing.
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s**g 发帖数: 66 | 5 Be patient, my friend.
Let me rephrase your OP:
You are trying to apply AC analysis to a ckt under such a 'bias' point,
which is only obtained through transient sim (periodic).
Here are my questions:
1. what is your switching freq? what is AC freq?
2. can you show your feedback ckt in the schematic?
There are different ways to attack this issue:
PSS + PAC may apply only when you try to study AC at a much lower freq than
switching frequency. But as you use it, your switch2 turns on/off all the
ti
【在 z*****h 的大作中提到】 : 多谢多谢 : 就是问在瞬态仿真的某个时间点仿开关电容电路的AC特性? : 如果有就可以直接说 : 下面的只是说明我用PSS+PAC仿真过,但发现结果并不是所要的,仅此而已 : switch1 A switch2 : GND ___/ _________/ ____ VDD : | : | : C === : |
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z*****h 发帖数: 547 | 6 很受教,谢谢
我觉得我的情况适用于你说的先仿tran,取得工作点后再仿AC吧
但是用voltage source会不会破坏了原始电路呢?
比如某些点的电压是靠电荷积累在对地寄生电容上的,AC仿真下可能并不等于0
你直接用voltage source那不就默认等于0了么?
than
【在 s**g 的大作中提到】 : Be patient, my friend. : Let me rephrase your OP: : You are trying to apply AC analysis to a ckt under such a 'bias' point, : which is only obtained through transient sim (periodic). : Here are my questions: : 1. what is your switching freq? what is AC freq? : 2. can you show your feedback ckt in the schematic? : There are different ways to attack this issue: : PSS + PAC may apply only when you try to study AC at a much lower freq than : switching frequency. But as you use it, your switch2 turns on/off all the
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s**g 发帖数: 66 | 7 Learn to use sp1tswtich:
dc_position vs ac_position.
Or try the old fashion: huge inductor in series to the voltage source. |
z*****h 发帖数: 547 | 8 多谢,我去analogLib里面试试
【在 s**g 的大作中提到】 : Learn to use sp1tswtich: : dc_position vs ac_position. : Or try the old fashion: huge inductor in series to the voltage source.
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