
11-11Energy Harvesting for Sensors
signal. Rectication is achieved by the alternate activation of one of the two converters. is circuit
re
quires
s
ome
c
ontrol
o
verhead
.
Fi
nally,
MP
PT
ci
rcuits
th
at
ma
ke
th
e
ha
rvester
wo
rk
as if it ha
d
an opt
imal
re
sistor
at it
s
ou
tput,
th
rough
re
sistor
em
ulation
as in RF (F
igure
11.6) or by se
tting
th
e
wo
rking
vo
ltage
to ha
lf
th
e
ha
rvester
op
en-circuit
vo
ltage
(V
OC
) [25], have also been proposed. In [25], they used switched capacitors to x the
ha
rvester’s
w
orking
v
oltage
a
t
0.5 V
OC
, where V
OC
needs to be periodically sampled.
e tr
end
in en
ergy
ha
rvesters
is to in
tegrate
se
veral
en
ergy
co
nditioning
ci
rcuits