<s>
Current	B-General_Concept
mode	I-General_Concept
logic	I-General_Concept
(	O
CML	O
)	O
,	O
or	O
source-coupled	B-General_Concept
logic	I-General_Concept
(	O
SCL	O
)	O
,	O
is	O
a	O
digital	O
design	O
style	O
used	O
both	O
for	O
logic	B-General_Concept
gates	I-General_Concept
and	O
for	O
board-level	O
digital	O
signaling	O
of	O
digital	B-General_Concept
data	I-General_Concept
.	O
</s>
<s>
The	O
principle	O
difference	O
between	O
CML	O
and	O
ECL	B-General_Concept
as	O
a	O
link	O
technology	O
is	O
the	O
output	O
impedance	O
of	O
the	O
driver	O
stage	O
:	O
the	O
emitter	O
follower	O
of	O
ECL	B-General_Concept
has	O
a	O
low	O
resistance	O
of	O
around	O
5	O
Ω	O
whereas	O
CML	O
connects	O
to	O
the	O
drains	O
of	O
the	O
driving	O
transistors	O
,	O
that	O
have	O
a	O
high	O
impedance	O
,	O
and	O
so	O
the	O
impedance	O
of	O
the	O
pull	O
up/down	O
network	O
(	O
typically	O
50	O
Ω	O
resistive	O
)	O
is	O
the	O
effective	O
output	O
impedance	O
.	O
</s>
<s>
CML	O
is	O
the	O
physical	B-Application
layer	I-Application
used	O
in	O
DVI	B-Protocol
,	O
HDMI	B-Protocol
and	O
FPD-Link	O
III	O
video	O
links	O
,	O
the	O
interfaces	O
between	O
a	O
display	O
controller	O
and	O
a	O
monitor	B-Device
.	O
</s>
<s>
In	O
addition	O
,	O
CML	O
has	O
been	O
widely	O
used	O
in	O
high-speed	O
integrated	O
systems	O
,	O
such	O
as	O
for	O
serial	B-Protocol
data	I-Protocol
transceivers	O
and	O
frequency	O
synthesizers	O
in	O
telecommunication	O
systems	O
.	O
</s>
<s>
The	O
fast	O
operation	O
of	O
CML	O
circuits	O
is	O
mainly	O
due	O
to	O
their	O
lower	O
output	O
voltage	O
swing	O
compared	O
to	O
the	O
static	O
CMOS	B-Device
circuits	O
,	O
as	O
well	O
as	O
the	O
very	O
fast	O
current	O
switching	O
taking	O
place	O
at	O
the	O
input	O
differential	O
pair	O
transistors	O
.	O
</s>
<s>
One	O
of	O
the	O
primary	O
requirements	O
of	O
a	O
current-mode	B-General_Concept
logic	I-General_Concept
circuit	O
is	O
that	O
the	O
current	O
bias	O
transistor	O
must	O
remain	O
in	O
the	O
saturation	O
region	O
to	O
maintain	O
a	O
constant	O
current	O
.	O
</s>
<s>
Studies	O
show	O
that	O
while	O
the	O
leakage	O
current	O
in	O
conventional	O
static	O
CMOS	B-Device
circuits	O
is	O
becoming	O
a	O
major	O
challenge	O
in	O
lowering	O
the	O
energy	O
dissipation	O
,	O
good	O
control	O
of	O
CML	O
current	O
consumption	O
makes	O
them	O
a	O
very	O
good	O
candidate	O
for	O
extremely	O
low	O
power	O
use	O
.	O
</s>
<s>
Called	O
subthreshold	O
CML	O
or	O
subthreshold	O
source	B-General_Concept
coupled	I-General_Concept
logic	I-General_Concept
(	O
STSCL	O
)	O
,	O
the	O
current	O
consumption	O
of	O
each	O
gate	O
can	O
be	O
reduced	O
down	O
to	O
a	O
few	O
tens	O
of	O
picoamps	O
.	O
</s>
