<s>
A	O
switched	B-Algorithm
capacitor	I-Algorithm
(	O
SC	O
)	O
is	O
an	O
electronic	O
circuit	O
that	O
implements	O
a	O
function	O
by	O
moving	O
charges	O
into	O
and	O
out	O
of	O
capacitors	O
when	O
electronic	O
switches	O
are	O
opened	O
and	O
closed	O
.	O
</s>
<s>
Filters	O
implemented	O
with	O
these	O
elements	O
are	O
termed	O
switched-capacitor	B-Algorithm
filters	I-Algorithm
,	O
which	O
depend	O
only	O
on	O
the	O
ratios	O
between	O
capacitances	O
and	O
the	O
switching	O
frequency	O
,	O
and	O
not	O
on	O
precise	O
resistors	O
.	O
</s>
<s>
SC	O
circuits	O
are	O
typically	O
implemented	O
using	O
metal	B-Architecture
–	I-Architecture
oxide	I-Architecture
–	I-Architecture
semiconductor	I-Architecture
(	O
MOS	O
)	O
technology	O
,	O
with	O
MOS	O
capacitors	O
and	O
MOS	B-Architecture
field-effect	I-Architecture
transistor	I-Architecture
(	O
MOSFET	B-Architecture
)	O
switches	O
,	O
and	O
they	O
are	O
commonly	O
fabricated	B-Architecture
using	O
the	O
complementary	O
MOS	O
(	O
CMOS	O
)	O
process	O
.	O
</s>
<s>
Common	O
applications	O
of	O
MOS	O
SC	O
circuits	O
include	O
mixed-signal	O
integrated	O
circuits	O
,	O
digital-to-analog	O
converter	O
(	O
DAC	O
)	O
chips	O
,	O
analog-to-digital	O
converter	O
(	O
ADC	O
)	O
chips	O
,	O
pulse-code	B-Algorithm
modulation	I-Algorithm
(	O
PCM	B-Algorithm
)	O
codec-filters	O
,	O
and	O
PCM	B-Algorithm
digital	B-General_Concept
telephony	I-General_Concept
.	O
</s>
<s>
The	O
simplest	O
switched-capacitor	B-Algorithm
(	O
SC	O
)	O
circuit	O
is	O
made	O
of	O
one	O
capacitor	O
and	O
two	O
switches	O
S	O
and	O
S	O
which	O
alternatively	O
connect	O
the	O
capacitor	O
to	O
either	O
in	O
or	O
out	O
at	O
a	O
switching	O
frequency	O
of	O
.	O
</s>
<s>
Finally	O
,	O
the	O
current	O
–	O
voltage	O
relationship	O
from	O
in	O
to	O
out	O
can	O
be	O
expressed	O
with	O
the	O
same	O
form	O
as	O
Ohm	O
's	O
law	O
,	O
to	O
show	O
that	O
this	O
switched-capacitor	B-Algorithm
circuit	I-Algorithm
simulates	O
a	O
resistor	O
with	O
an	O
equivalent	O
resistance	O
of	O
:	O
</s>
<s>
Because	O
the	O
resistance	O
inside	O
electric	O
switches	O
is	O
typically	O
much	O
smaller	O
than	O
the	O
resistances	O
in	O
circuits	O
relying	O
on	O
regular	O
resistors	O
,	O
SC	O
circuits	O
can	O
have	O
substantially	O
lower	O
Johnson	O
–	O
Nyquist	O
noise	B-Algorithm
.	O
</s>
<s>
However	O
harmonics	O
of	O
the	O
switching	O
frequency	O
may	O
be	O
manifested	O
as	O
high	O
frequency	O
noise	B-Algorithm
that	O
may	O
need	O
to	O
be	O
attenuated	O
with	O
a	O
low-pass	B-Algorithm
filter	I-Algorithm
.	O
</s>
<s>
using	O
an	O
configurable	O
clock	O
output	O
signal	O
from	O
a	O
microcontroller	B-Architecture
)	O
.	O
</s>
<s>
Electronic	B-Architecture
filters	I-Architecture
consisting	O
of	O
resistors	O
and	O
capacitors	O
can	O
have	O
their	O
resistors	O
replaced	O
with	O
equivalent	O
switched-capacitor	B-Algorithm
simulated	O
resistors	O
,	O
allowing	O
the	O
filter	B-Architecture
to	O
be	O
manufactured	O
using	O
only	O
switches	O
and	O
capacitors	O
without	O
relying	O
on	O
real	O
resistors	O
.	O
</s>
<s>
Switched-capacitor	B-Algorithm
simulated	O
resistors	O
can	O
replace	O
the	O
input	O
resistor	O
in	O
an	O
op	O
amp	O
integrator	O
to	O
provide	O
accurate	O
voltage	O
gain	O
and	O
integration	O
.	O
</s>
<s>
This	O
switched-capacitor	B-Algorithm
circuit	I-Algorithm
is	O
called	O
"	O
parasitic-sensitive	O
"	O
because	O
its	O
behavior	O
is	O
significantly	O
affected	O
by	O
parasitic	O
capacitances	O
,	O
which	O
will	O
cause	O
errors	O
when	O
parasitic	O
capacitances	O
ca	O
n't	O
be	O
controlled	O
.	O
</s>
<s>
One	O
useful	O
characteristic	O
of	O
switched-capacitor	B-Algorithm
circuits	I-Algorithm
is	O
that	O
they	O
can	O
be	O
used	O
to	O
perform	O
many	O
circuit	O
tasks	O
at	O
the	O
same	O
time	O
,	O
which	O
is	O
difficult	O
with	O
non-discrete	O
time	O
components	O
(	O
i.e.	O
</s>
<s>
Switched-capacitor	B-Algorithm
circuits	I-Algorithm
are	O
analysed	O
by	O
writing	O
down	O
charge	O
conservation	O
equations	O
,	O
as	O
in	O
this	O
article	O
,	O
and	O
solving	O
them	O
with	O
a	O
computer	O
algebra	O
tool	O
.	O
</s>
<s>
For	O
hand	O
analysis	O
and	O
for	O
getting	O
more	O
insight	O
into	O
the	O
circuits	O
,	O
it	O
is	O
also	O
possible	O
to	O
do	O
a	O
Signal-flow	O
graph	O
analysis	O
,	O
with	O
a	O
method	O
that	O
is	O
very	O
similar	O
for	O
switched-capacitor	B-Algorithm
and	O
continuous-time	O
circuits	O
.	O
</s>
