<s>
A	O
bias	B-Algorithm
tee	I-Algorithm
is	O
a	O
three-port	O
network	O
used	O
for	O
setting	O
the	O
DC	O
bias	O
point	O
of	O
some	O
electronic	O
components	O
without	O
disturbing	O
other	O
components	O
.	O
</s>
<s>
The	O
bias	B-Algorithm
tee	I-Algorithm
is	O
a	O
diplexer	O
.	O
</s>
<s>
Conceptually	O
,	O
the	O
bias	B-Algorithm
tee	I-Algorithm
can	O
be	O
viewed	O
as	O
an	O
ideal	O
capacitor	O
that	O
allows	O
AC	O
through	O
but	O
blocks	O
the	O
DC	O
bias	O
and	O
an	O
ideal	O
inductor	O
that	O
blocks	O
AC	O
but	O
allows	O
DC	O
.	O
</s>
<s>
Although	O
some	O
bias	B-Algorithm
tees	I-Algorithm
can	O
be	O
made	O
with	O
a	O
simple	O
inductor	O
and	O
capacitor	O
,	O
wideband	O
bias	B-Algorithm
tees	I-Algorithm
are	O
considerably	O
more	O
complicated	O
because	O
practical	O
components	O
have	O
parasitic	O
elements	O
.	O
</s>
<s>
Bias	B-Algorithm
tees	I-Algorithm
are	O
designed	O
for	O
transmission-line	O
environments	O
.	O
</s>
<s>
Bias	B-Algorithm
tees	I-Algorithm
are	O
designed	O
to	O
operate	O
over	O
a	O
range	O
of	O
signal	O
frequencies	O
.	O
</s>
<s>
For	O
wide-range	O
bias	B-Algorithm
tees	I-Algorithm
,	O
the	O
inductive	O
reactance	O
must	O
be	O
large	O
in	O
value	O
,	O
even	O
at	O
the	O
lowest	O
frequency	O
,	O
hence	O
the	O
dimensions	O
of	O
the	O
inductor	O
must	O
be	O
large	O
in	O
size	O
.	O
</s>
<s>
At	O
a	O
high	O
enough	O
frequency	O
,	O
the	O
stray	O
capacitance	O
presents	O
a	O
low-impedance	O
shunt	O
path	O
for	O
the	O
RF	O
signal	O
,	O
and	O
the	O
bias	B-Algorithm
tee	I-Algorithm
becomes	O
ineffective	O
.	O
</s>
<s>
Practical	O
wide-band	O
bias	B-Algorithm
tees	I-Algorithm
must	O
use	O
elaborate	O
circuit	O
topologies	O
to	O
avoid	O
the	O
shunt	O
path	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
Picosecond	O
Pulse	O
Labs	O
model5580	O
bias	B-Algorithm
tee	I-Algorithm
works	O
from	O
10kHz	O
to	O
15GHz	O
.	O
</s>
<s>
Johnson	O
gives	O
an	O
example	O
of	O
a	O
wideband	O
microstrip	O
bias	B-Algorithm
tee	I-Algorithm
covering	O
50kHz	O
to	O
1GHz	O
using	O
four	O
inductors	O
(	O
330nH	O
,	O
910nH	O
,	O
18μH	O
,	O
and	O
470μH	O
)	O
in	O
series	O
.	O
</s>
<s>
His	O
design	O
cribbed	O
from	O
a	O
commercial	O
bias	B-Algorithm
tee	I-Algorithm
.	O
</s>
<s>
To	O
show	O
the	O
advantage	O
of	O
additional	O
components	O
,	O
Johnson	O
provided	O
a	O
simulation	O
of	O
a	O
bias	B-Algorithm
tee	I-Algorithm
that	O
used	O
just	O
inductors	O
and	O
capacitors	O
without	O
suppression	O
.	O
</s>
<s>
A	O
bias	B-Algorithm
tee	I-Algorithm
is	O
used	O
to	O
insert	O
DC	O
power	O
into	O
an	O
AC	O
signal	O
to	O
power	O
remote	O
antenna	O
amplifiers	O
or	O
other	O
devices	O
.	O
</s>
<s>
It	O
is	O
usually	O
positioned	O
at	O
the	O
receiving	O
end	O
of	O
the	O
coaxial	O
cable	O
to	O
pass	O
DC	O
power	O
from	O
an	O
external	O
source	O
to	O
the	O
coaxial	O
cable	O
running	O
to	O
powered	B-Device
device	I-Device
.	O
</s>
<s>
A	O
bias	O
"	O
T	O
"	O
consists	O
of	O
a	O
feed	O
inductor	O
to	O
deliver	O
DC	O
to	O
a	O
connector	B-Protocol
on	O
the	O
device	O
side	O
and	O
a	O
blocking	O
capacitor	O
to	O
keep	O
DC	O
from	O
passing	O
through	O
to	O
the	O
receiver	O
.	O
</s>
<s>
The	O
RF	O
signal	O
is	O
connected	O
directly	O
from	O
one	O
connector	B-Protocol
to	O
the	O
other	O
with	O
only	O
the	O
blocking	O
capacitor	O
in	O
series	O
.	O
</s>
<s>
Bias	B-Algorithm
tees	I-Algorithm
are	O
used	O
in	O
a	O
variety	O
of	O
applications	O
,	O
but	O
are	O
generally	O
used	O
to	O
provide	O
an	O
RF	O
signal	O
and	O
(	O
DC	O
)	O
power	O
to	O
a	O
remote	O
device	O
where	O
running	O
two	O
separate	O
cables	O
would	O
not	O
be	O
advantageous	O
.	O
</s>
<s>
Biasing	O
is	O
often	O
used	O
with	O
photodiodes	O
(	O
vacuum	O
and	O
solid	O
state	O
)	O
,	O
Microchannel	O
plate	O
detectors	O
,	O
transistors	B-Application
,	O
and	O
triodes	O
,	O
so	O
that	O
high	O
frequencies	O
from	O
the	O
signal	O
do	O
not	O
leak	O
into	O
a	O
common	O
power	O
supply	O
rail	O
.	O
</s>
<s>
Other	O
examples	O
include	O
:	O
Power	B-Device
over	I-Device
Ethernet	I-Device
,	O
active	O
antennas	O
,	O
low-noise	O
amplifiers	O
,	O
and	O
down	O
converters	O
.	O
</s>
<s>
The	O
telephone	O
line	O
for	O
plain	O
old	O
telephone	O
service	O
and	O
some	O
early	O
microphones	O
use	O
a	O
bias	B-Algorithm
tee	I-Algorithm
circuit	O
—	O
often	O
with	O
a	O
gyrator	O
replacing	O
the	O
inductor	O
—	O
this	O
enables	O
a	O
thin	O
cable	O
with	O
only	O
2	O
conductors	O
to	O
send	O
power	O
from	O
the	O
system	O
to	O
the	O
device	O
,	O
and	O
send	O
audio	O
from	O
the	O
device	O
back	O
to	O
the	O
system	O
.	O
</s>
<s>
Modern	O
microphones	O
often	O
use	O
3	O
conductors	O
in	O
a	O
phantom	B-Algorithm
power	I-Algorithm
circuit	O
very	O
similar	O
to	O
a	O
bias	B-Algorithm
tee	I-Algorithm
circuit	O
.	O
</s>
<s>
There	O
are	O
several	O
bias	B-Algorithm
tee	I-Algorithm
designs	O
.	O
</s>
