The dependence of the generation frequency on the gas concentrations is
determined by the feedback loop according to the equivalent circuit. The
transformation function is described by the expression
(
)
2
2
2
2
1
1
5
1
2
1
2
2
2
2
5
1
2
4
()
1
,
2
2
()
bx
G
HG
bx
bx
bx
bx
G
HG
bx
A
A
RCCRCCC
C
C
F
RCCRCCC
+
+
+
=
(16)
where
2
2
2
2
2
2
1
2
5
1
2
1
5
1
2
()
()
.
G
bx
HG
HG
bx
bx
bx
G
HG
bx
bx
A
RCCC
RCCC
CRCC
RCCC
=
+
+
−
The sensitivity of the transducer is determined on the basis of expression (16)
and is described by the equation
(
(
)
(
)
2
2
2
1
2
2
1
2
1
2
22
2
1
2
1
2
5
2
11
1
()
()
2
2
()
2
()
8
1
()
()
2
2
()
2
()
2
()
8
4
/
()
2
F
G
HG
C
bx
HG
G
bx
HG
G
G
G
bx
HG
G
bx
HG
G
G
bx
bx
HG
G
RC
R
C
S
CC
RC
CC
RC
C
C
RC
RC
B
C
C
RC
C
C
RC
C
C
RC
B
B
B
RCCCC
RC
C
BB
=
+
+
+
+
+
+
+
−
+
−
2
2
1
1
2
2
2
3
2
2
2
5
1
2
5
1
2
()
4
4
,
()
()
G
bx
bx
HG
G
bx
bx
HG
G
RC
B
B
B
B
C
RCCCC
RC
RCCCC
RC
+
++
(17)
where
2
2
2
2
2
2
1
2
5
1
2
1
5
1
2
()
()
,
G
bx
HG
HG
bx
bx
bx
G
HG
bx
bx
B
RCCC
RCCC
CRCC
RCCC
=
+
+
−
2
2
2
2
5
1
2
1
2
(
)
().
bx
bx
bx
bx
HG
G
B
RC
C
CCCCRC
=+
The graph of the sensitivity dependence on the concentration of gas is shown in
Figure 14.
Figure 14. Dependence of sensitivity on gas concentration
According to the schedule, the highest sensitivity of the device ranges from
100 ppm to 300 ppm and has a value of 500 Hz/ppm, and at values of concentration
- 497 -