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Simulators >> Circuit Simulators >> how to give pulse
https://designers-guide.org/forum/YaBB.pl?num=1245600983

Message started by raja.cedt on Jun 21^st, 2009, 9:16am

Title: how to give pulse
Post by raja.cedt on Jun 21^st, 2009, 9:16am

hi,
can anybody please tell me how to give a pulse with variable frequency in hspice, i know that PWL will work but very lengthy...

Thanks,
Rajasekhar.

Title: Re: how to give pulse
Post by pancho_hideboo on Jun 21^st, 2009, 10:04pm

raja.cedt wrote on Jun 21^st, 2009, 9:16am:

can anybody please tell me how to give a pulse with variable frequency in hspice, i know that PWL will work but very lengthy....

I can't understand what you are confusing.

Use pulse() like following.

Quote:

.param Vlow=0.0 Vhigh=3.0
.param fclk=100MHz
.param Tperiod='1/fclk'
.param Tdelay=0.0
.param duty=0.5
.param Trise='Tperiod/20'
.param Tfall='Tperiod/20'
.param Twidth='Tperiod*duty-(Trise+Tfall)/2'

vpulse 1 0 pulse( Vlow Vhigh Tdelay Trise Tfall Twidth Tperiod )

Title: Re: how to give pulse
Post by raja.cedt on Jun 22^nd, 2009, 1:46am

hi i am sorry, i mean to say that i want some frequency till some time after that i need another frequency..

Thanks,
Rajasekhar.

Title: Re: how to give pulse
Post by pancho_hideboo on Jun 22^nd, 2009, 2:20am

raja.cedt wrote on Jun 22^nd, 2009, 1:46am:

hi i am sorry, i mean to say that i want some frequency till some time after that i need another frequency.

Create signal sources using Verilog-A.
It is very easy to generate such signals if you use $abstime, @timer() and transition() in Verilog-A.

If frequency variation is continuous, you can use FM-signal source and limitter to generate pulse signal of continuous FM without using Verilog-A model.

As another method, you can use signals based on VCD(Value Change Dump) format data.
This method is also implemented in both Cadence Spectre and Agilent GoldenGate.

http://www.designers-guide.org/Forum/YaBB.pl?num=1207062028/4#4

Currently almost all commercial transient simulator have an ability of generating signal based on VCD(Value Change Dump) format data.