Data sheet
Please read cautions and warnings and
January 25, 2013 important notes at the end of
this document.
ESD protection of SAW filters
SAW filters are Electro Static Discharge sensitive devices. To reduce the probability of damages
caused by ESD, special matching topologies have to be applied.
In general, “ESD matching” has to be ensured at that filter port, where electrostatic discharge is
expected.
Electrostatic discharges predominantly appear at the antenna input of RF receivers. Therefore only
the input matching of the SAW filter has to be designed to short circuit or to block the ESD pulse.
Below three figures show recommended “ESD matching” topologies.
For wideband filters the high-pass ESD matching structure needs to be at least of 3
rd
order to
ensure a proper matching for any impedance value of antenna and SAW filter input. The required
component values have to be determined from case to case.
Cs1 Cs3 Cs1 Cs3
Fig. 1 MLC varistor plus ESD matching Fig. 2 Suppressor diode plus ESD matching
In cases where minor ESD occur, following simplified “ESD matching” topologies can be used
alternatively.
