SEMIFILT SC Series-Distributed Constant Type Filter
DCT Type Noise Filter
The composition of conventional noise
filters consists of a combination of induc-
tance (L) and capacitance (C).
Typically, the equivalent circuit for these
filters is one of the "Lumped Constant
Circuit" type where a by-pass capacitor
is used in conjunction with an inductor.
See Figure 2.
The new "DCT" noise filters (SEMIFILT)
are unique in that they employ a
"Distributed Constant Circuit" type where
the capacitance and inductance are
combined to form an integrated capaci-
tive/inductive circuit as shown in Figure 1.
When conventional noise filters (Lumped
Constant type) are not achieving suffi-
cient noise reduction,our SC series can
directly replace these filters without any
adverse effects on circuit characteristics.
SEMIFILT SC series are available in sev-
eral series,each covering various fre-
SEMIFILT SC series have also shown
excellent protection against EMI noise
from various external electronic appli-
Conceptual Structure of SC/SP Series
SC DCT noise filters (SEMIFILT SC
Series)are constructed by winding two
conductors with an interlayer of dielectric
material. High attenuation characteristics
are achieved by continuous integration of
the L and C.
Directional Noise Reduction Effect
High frequency noise injected through
terminal generates an electromotive
Due to the proximity of the ground con-
nection, line responds as a bypass
capacitor and shunts the unwanted noise
In the alternate case, when a high fre-
quency noise is injected into terminal ,
the bypass effect is decreased. This is
due to the fact that line at its terminat-
ed end is responding more as an induc-
tor, with less bypass capacitance. The
high frequency noise is attenuated by the
inductive effect of the main line itself.