
13-16 Sensors and Sensor Technology
13.3.5 Smart Thermal Flow Sensors and Advanced Evaluation Circuits
Conventional sensors usually have separate electronics, which causes high cost and prevents large
se
rial
pr
oduction
. An in
tegrated
sm
art
th
ermal
o
w
se
nsor
is de
ned
as a ch
ip
th
at
co
ntains
on
e
or
mo
re
se
nsors,
si
gnal
co
nditioning,
A/
D
co
nversion,
an
d
a bu
s
ou
tput
[6
]
. e
refore,
th
ere
is a ne
ed
fo
r
ad
vanced
ev
aluation
me
thods
th
at
co
nvert
th
e
th
ermal
si
gnal
di
rectly
in
to
a fr
equency
an
d
du
ty-
cycle
ou
tput
.
13.3.6 Duty-Cycle Modulation for the Hot-Wire Sensors
e constant heater temperature can be controlled by modulation of the amplitude of