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Design >> RF Design >> How to do SP simulation with non-resistive termina
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Message started by zhangjerome on Apr 16^th, 2007, 6:31pm

Title: How to do SP simulation with non-resistive termina
Post by zhangjerome on Apr 16^th, 2007, 6:31pm

Now my circuit has a capacitive load and I want to do SP simulation. But the port can only have a
real impedance. What should I do?

Title: Re: How to do SP simulation with non-resistive ter
Post by Andrew Beckett on Apr 16^th, 2007, 10:12pm

Use a more recent version of port. This has other parameters:

Port parameters:
55 r=50 Ohm Reference resistance.
56 x=0 Ohm Reference reactance, ignored for time domain analyses.
57 lchock=0.1 H Chock inductor for network analyser.
58 cblock=0.0001 F Blocking capacitance for network analyser.

Regards,

Andrew.

Title: Re: How to do SP simulation with non-resistive ter
Post by Ken Kundert on Apr 16^th, 2007, 10:50pm

Andrew,
What is a chock inductor? And what are lchock and cblock used for? They have non-zero defaults, does that imply that they are always present?

-Ken

Title: Re: How to do SP simulation with non-resistive ter
Post by Andrew Beckett on Apr 16^th, 2007, 10:53pm

Ken,

Good question. I'd not noticed them until I just looked at the help just now. I'll see what I can find and report back.

Andrew.

Title: Re: How to do SP simulation with non-resistive ter
Post by ACWWong on Apr 17^th, 2007, 2:54am

cadence must mean choke inductor (perhaps they like chock because it rhymes with block ???)

i must admit i have never noticed an impact of a fixed 0.1H or 1mF in sp sweeps i've ever done in the past or recently....

Title: Re: How to do SP simulation with non-resistive ter
Post by Andrew Beckett on Apr 17^th, 2007, 9:31am

I looked a bit further up the help for port:

Quote:

You can define 2 or 3 terminal port. if you define 2-terminal port it operates like was described above. In case of 3-terminal port it also includes internal ideal chock inductor and ideal blocking capacitor. They are work like switches to terminate or connect appropriate branch dependent on type of analysis

You're right about the fact that it should be "choke" inductor - there is a PCR (923338) for this typo to be corrected (and for the grammar errors to be corrected too!). They are only included if you use a 3 terminal port. This was added for compatibility with other SPICE simulators (which have a .net or vport component, or something like that...)

Regards,

Andrew.