[SI-LIST] Re: using spice to calculate driver output impedance
- From: Steve Weir <weirsi@xxxxxxxxxx>
- To: "Eric Steimle" <steimle@xxxxxxxxxxxxx>
- Date: Thu, 24 Feb 2005 09:28:56 -0800
Eric, in a word, yes. You may obtain SPICE tools with limited capability
at low or zero cost. Your life will be much better is you take advantage
of one. Otherwise, you can use MathCad or even Excel to do the matrix
arithmetic much more slowly and painfully.
Steve
At 09:38 AM 2/24/2005 -0500, Eric Steimle wrote:
>Ah ok the vector math makes a lot of sense, I don't know where the
>30Ohms comes from though. Taking this same route does this then mean
>that the on die capacitance (C_comp of the driver) presents a certain
>amount of impedance to the signal that can also be represented as a
>vector that I can add to my total Zout?
>
>Thanks
>Eric
>
>BTW I did this equation which I think is right to add the inductance of
>the bond wire. Zbond+Zdriver = (14.5+j0) + (0+j8.8) = 16.9Ohms. You
>made me pull out my text books to relearn that one :) Thanks again for
>your help.
>
>
>
>-----Original Message-----
>From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
>On Behalf Of Steve Weir
>Sent: Wednesday, February 23, 2005 8:14 PM
>To: ericsilist@xxxxxxxxx; si-list@xxxxxxxxxxxxx
>Subject: [SI-LIST] Re: using spice to calculate driver output impedance
>
>Eric, the inductive reactance will not add linearly. Do the vector
>addition and you will find that the resistor value will be a lot closer
>to
>the 35.5 ohms that the resistive slope would lead to by itself. Off the
>
>top of my head, I think you will find 30-33 ohms about right.
>
>Steve
>At 04:11 PM 2/22/2005 -0800, eric steimle wrote:
> >Hi all, I'm having some trouble thinking of the right
> >way to calculate driver impedance using spice. I have
> >finally a functioning model of the driver in question
> >and I've been able to run some simulations with it. I
> >was hoping that there might be an accepted way of
> >calculating driver impedance out there that I don't
> >know about, or perhaps some literature you could point
> >me to. Any help would be greatly appreciated.
> >
> >Best Regards,
> >Eric
> >
> >
> >
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