why interconnect dont have inductance

we all know that whenever we speak of interconnects ,we say that interconnect has some Resistance,some capacitance but not inductance ......why interconnects dont have L

pandit_vlsi said:

we all know that whenever we speak of interconnects ,we say that interconnect has some Resistance,some capacitance but not inductance ......why interconnects dont have L

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Interconnect has inductance and is it causes voltage drop. But I guess it doesnt really affect the propagation delay.. that may be why its not mentioned in the context of synthesis..

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Hi pandit_vlsi,

Interconnect has everything, include microwave raditation. However, at dfiferent geometry size and frequency of operation, some parameters are not important. By omitting the unimportant parameters, the design can be done many many times faster while using much less resource.

To give an example, in digital 0.35um, only C is considered. In 0.13um (possibly 90nm and 65um), only C and R are considered.

It is not easy to take L into consideration.

Regards,
Eng Han

Hi,

If the time of flight is greater than signal rise/fall times then Inductance comes into play in interconnect.

If the time of flight is less than signal rise/fall times then resistanc,capacitance or RC network comes into play provided the interconnects are longer.

pandit_vlsi said:

we all know that whenever we speak of interconnects ,we say that interconnect has some Resistance,some capacitance but not inductance ......why interconnects dont have L

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as a continuation,total propagation delay can be calculated which is depends on RC.that delay is called as Elmore's constant

i didnot get time of flight....what is this time of flight

Inductance effects on interconnects are have to considered when operating frequency

goes higher and we move to finer geometries. I guess timeof flight may be the time

taken for the signal to come from die-package-pcb-package-die.Since inductance can

be caliculated in a loop only we need to consider the time 0f flight.

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