Hardware Reference
In-Depth Information
V
0
V
01
V
02
¼
V
02
I
x
2
¼
ð
15
:
27
Þ
R
1
R
1
V
0
R
2
V
01
R
2
¼
I
z
2
¼
ð
15
:
28
Þ
and setting I
x2
¼
I
z2
, which leads to the following values of V
TL
and V
TH
V
0
R
1
R
2
V
TH
¼
V
TL
¼
1
ð
15
:
29
Þ
The amplitude (peak-to-peak) of the triangular wave form is given by:
V
0
R
1
R
2
V
02
¼
ð
V
TH
V
TL
Þ
¼
21
ð
15
:
30
Þ
The periods of the square and triangular waves are given by:
2
R
3
C
1
ð
ð
R
1
=
R
2
Þ
Þ
T
1
¼
ð
15
:
31
Þ
V
c
2
R
3
C
1
ð
ð
R
1
=
R
2
Þ
Þ
T
2
¼
ð
15
:
32
Þ
2
V
c
Finally, the oscillation frequency (f
0
) and duty cycle (D
a
) are given by:
1
T
1
þ
V
C
2
ð
V
C
Þ
f
0
¼
T
2
¼
ð
15
:
33
Þ
4
R
3
C
1
ð
ð
R
1
=
R
2
Þ
Þ
T
1
T
1
þ
V
C
2
D
a
¼
T
2
¼
ð
:
Þ
1
15
34
where
V
B
V
0
V
C
¼
1
ð
15
:
35
Þ
It is interesting to note that f
0
can be independently controlled by R
3
thereby
resulting in single resistance controlled oscillator. Also, the amplitude of the
triangular wave is proportional to the ratio (R
1
/R
2
) whereas the duty cycle is
controllable by the control voltage V
c
. Furthermore, if one takes V
c
<<
1 the
interval T
2
is negligibly small and can be ignored and the circuit can then be used
as saw-tooth waveform generator for which the frequency of oscillation is given by:
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