**From:** Chandan (*chandan_career@yahoo.com*)

**Date:** Wed May 23 2001 - 02:00:07 PDT

**Next message:**Khanh Le: "Re: [SI-LIST] : Antenna Problem on the Board"**Previous message:**Sunil Kumar: "Re: [SI-LIST] : Antenna Problem on the Board"**Next in thread:**Degerstrom, Michael J.: "RE: [SI-LIST] : EFFECT OF LUMPED LOAD ON TRANSMISSION LINES"**Maybe reply:**Degerstrom, Michael J.: "RE: [SI-LIST] : EFFECT OF LUMPED LOAD ON TRANSMISSION LINES"**Maybe reply:**Degerstrom, Michael J.: "RE: [SI-LIST] : EFFECT OF LUMPED LOAD ON TRANSMISSION LINES"**Maybe reply:**Degerstrom, Michael J.: "RE: [SI-LIST] : EFFECT OF LUMPED LOAD ON TRANSMISSION LINES"**Maybe reply:**Degerstrom, Michael J.: "RE: [SI-LIST] : EFFECT OF LUMPED LOAD ON TRANSMISSION LINES"

Hi,

Consider a long trace - long enough for it to be

considered as a transmission line. Let this trace be

connected between a CMOS driver & a CMOS receiver. The

receiver can therefore be modeled as a capacitive

load at the end of the line.

1. Should this capacitor be considered as a lumped

element or distributed?

This question assumes importance when point-to-point

clock traces are routed between a synthesizer & a

receiver. Ideally, the value of series (or source)

termination resistance that must be used is the

difference between the characteristic impedance and

the driver's internal resistance. I was wondering if I

should use the loaded characteristic impedance or

unloaded characteristic impedance. I then began to

wonder if I should consider the load as distributed or

lumped. Kindly comment.

2. Does the lumped capacitance affect the properties

of a transmission line? If so, how?

3. The following approximation describes the

relationship between the loaded characteristic

impedance, unloaded characteristic impedance and

the value of DISTRIBUTED capacitance:

Z0' = Z0/ROOT OF (1 + CL/CO)

where Z0' = Loaded characteristic impedance

Z0 = Unloaded (Intrinsic) characteristic impedance

CL = Load capacitance/unit length

C0 = Intrinsic capacitance/unit length

Is there any relationship between loaded

characteristic impedance, unloaded characteristic

impedance and the value of LUMPED capacitance?

Thanks,

Chandan

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**Next message:**Khanh Le: "Re: [SI-LIST] : Antenna Problem on the Board"**Previous message:**Sunil Kumar: "Re: [SI-LIST] : Antenna Problem on the Board"**Next in thread:**Degerstrom, Michael J.: "RE: [SI-LIST] : EFFECT OF LUMPED LOAD ON TRANSMISSION LINES"**Maybe reply:**Degerstrom, Michael J.: "RE: [SI-LIST] : EFFECT OF LUMPED LOAD ON TRANSMISSION LINES"**Maybe reply:**Degerstrom, Michael J.: "RE: [SI-LIST] : EFFECT OF LUMPED LOAD ON TRANSMISSION LINES"**Maybe reply:**Degerstrom, Michael J.: "RE: [SI-LIST] : EFFECT OF LUMPED LOAD ON TRANSMISSION LINES"**Maybe reply:**Degerstrom, Michael J.: "RE: [SI-LIST] : EFFECT OF LUMPED LOAD ON TRANSMISSION LINES"

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