Does anybody know how to simulate loopgain using HSPICE?

[pcaocn]

hi guys,

My professor required us to do it using LTSPICE, which has a testbench for calculating loopgain in feedback.

Does anybody know how to do it in Hspice? If someone can share a piece of netlist, that will be appreciated.

Thanks.

 

[leo_o2]

Pls do AC analysis and break the loop with big inductor(>1GH) and inject a AC source into it.

 

[LvW]

This item has been discussed extensively and very often within this forum.
Please, spend some minutes for searching here or via google.

 

[pcaocn]

Sorry for my laziness, I will do it. So sorry...
Thanks anyway.

 

[LvW]

No problem. However, if you have a specific question in this context (because sometimes it can be a tricky task) you can/should try it again here.

 

[test_123]

in new version hspice, it has stb analysis

 

[haykding]

hi guys,

My professor required us to do it using LTSPICE, which has a testbench for calculating loopgain in feedback.

Does anybody know how to do it in Hspice? If someone can share a piece of netlist, that will be appreciated.

Thanks.

You can use LSTB analysis (last version of HSPICE supports it).
Here is example. Break the loop with DC voltage source (dc=0) and add this line to your deck .LSTB mode=single vsource=V[voltage source name] (must use with AC analysis).
And for probing use following
· .probe AC LSTB(db) LSTB(p)
· .measure LSTB gm gain_margin
· .measure LSTB pm phase_margin
· .measure LSTB adc loop_gain_minifreq
· .measure LSTB f0 unity_gain_freq