Anto,
As Larry pointed out at different points in the systems the actual wave
shapes will be different. It is more spike-like on the silicon, but
with the clock frequency that will get filtered out by the package-board
interface. The current is more step-like on the board after the
package-board filtering.
In recent years several publications appeared about rouge waves in an
attempt to come up with the worst-case noise. However, the worst-case
noise can be calculated based on a simple process published a while ago;
the same fundamental process that is used in signal integrity to
calculate what is called the peak distortion analysis.
Regards,
Istvan Novak
Oracle
On 4/29/2015 10:13 AM, Anto Davis wrote:
Hi,
I have a doubt,
Please look at the link below:
ednTargetImpedance
<http://www.edn.com/design/test-and-measurement/4413192/3/Target-impedance-based-solutions-for-PDN-may-not-provide-a-realistic-assessment>
Why is the switching excitation pattern a sharp edged trapezoidal instead
of a 10% triangular waveform at some processor frequency?
At least it should have been modulated with this pattern, or randomized it.
Say because of the microprocessor operations, lower frequencies are
excited, it will look like a modulated wave.
But in this case also, the amplitude of lower frequency currents will be
very small right?
Is there any entity in an IC draws this type of current waveforms?
I have a related doubt, what is the nature of current taken by a Current-
Mode differential signaling driver? Is it constant in all the time it
operates?
Thanks,
Anto
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