**From:** Gary Peterson (*Gary_Peterson@Emcore.com*)

**Date:** Wed Nov 01 2000 - 12:50:37 PST

**Next message:**Ed Priest: "RE: [SI-LIST] : effect of trace width on the performance"**Previous message:**George Shaw: "Re: [SI-LIST] : effect of trace width on the performance"**Next in thread:**Charles Grasso: "Re: [SI-LIST] : differential impedance calculations"**Reply:**Charles Grasso: "Re: [SI-LIST] : differential impedance calculations"**Reply:**Brad Underwood: "Re: [SI-LIST] : differential impedance calculations"**Maybe reply:**Larry Miller: "RE: [SI-LIST] : differential impedance calculations"**Maybe reply:**Larry Miller: "RE: [SI-LIST] : differential impedance calculations"**Maybe reply:**Jason Xiao: "RE: [SI-LIST] : differential impedance calculations"**Maybe reply:**Dan Swanson: "RE: [SI-LIST] : differential impedance calculations"

I seem to recall Dr. Howard Johnson mentioning that impedance calculation

formulas made assumptions (since closed-form solutions aren't possible).

Can someone comment on assumptions made for the equation for differential

impedance shown below? Seems to me that as traces get closer together, the

single ended impedance would be affected. When I calculate single-point

values for differential impedance using Hyperlynx LineSim, I do see the

single-ended impedance change when the spacing between the pair gets small.

Thanks,

Gary Peterson

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**Next message:**Ed Priest: "RE: [SI-LIST] : effect of trace width on the performance"**Previous message:**George Shaw: "Re: [SI-LIST] : effect of trace width on the performance"**Next in thread:**Charles Grasso: "Re: [SI-LIST] : differential impedance calculations"**Reply:**Charles Grasso: "Re: [SI-LIST] : differential impedance calculations"**Reply:**Brad Underwood: "Re: [SI-LIST] : differential impedance calculations"**Maybe reply:**Larry Miller: "RE: [SI-LIST] : differential impedance calculations"**Maybe reply:**Larry Miller: "RE: [SI-LIST] : differential impedance calculations"**Maybe reply:**Jason Xiao: "RE: [SI-LIST] : differential impedance calculations"**Maybe reply:**Dan Swanson: "RE: [SI-LIST] : differential impedance calculations"

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