Series Rc Filter For Esd Mitigation On Asynchronous Nets; Frequency Response Of The Series Rc Filter - Intel Quark SoC X1000 Design Manual

Electrostatic Discharge (ESD)—Intel
coupled ESD noises show alternative behaviors. These noises typically have lower
voltage level (<10 V). They do not activate the aforementioned ESD protection circuits,
such as ESD diode, but are still capable of upsetting the system. Therefore, they may
have very limited effects against such ESD events.
A series RC filter may be applied sensitive asynchronous nets to enhance the system
robustness under such circumstances. This filter can reject high-frequency components
in injected ESD noise even when ESD diodes are not activated. The peak voltage and
current may be significantly reduced. Due to the low-pass nature of this filter, Intel
does not recommend applying this filter to high-speed links. This filter may degrade
signal integrity of high speed signaling.
The schematic of this filter is shown in
capacitors and resistors, shunted from the signal line to the ground. Intel recommends
the component values of R=10 and C=100 nF for a 50- transmission line. The
frequency response of this filter is depicted in
around 10 KHz, while the knee point is around 100 MHz. This suppresses high-
frequency components of ESD noise with negligible impacts to asynchronous signaling.
Intel's recommendation provides the typical value as a starting point. The components
value may be adjusted accordingly to meet pin/signal requirements. It is noted that
this filter needs to be placed within 100 mil form the victims (sensitive IC pins) as
possible, to ensure the protection effectiveness.
Figure 77.

Series RC Filter for ESD Mitigation on Asynchronous Nets

Figure 78.

Frequency Response of The Series RC Filter

June 2014
Order Number: 330258-002US
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Quark™ SoC X1000
Figure 77. It is a combination of series
Figure 78. The first pole can be found
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