Hardware Reference
In-Depth Information
a
b
c
V
0
V
0
Path 1
Path 1
I
z
+
V
0
+
V
0
z
V
0
y
2
DVCC
DPDT
switch
V
in
V
in
R
2
R
1 2
0
Path2
V
−
0
V
TL
V
TH
3
1
V
TL
V
TH
y
1
x
Path2
V
in
V
−
4
I
x
Fig. 15.9 (a) Switch-controllable DVCC-based bistable multivibrator (b) transfer characteristics
in CW mode (c) transfer characteristics in CCW mode (Adapted from [
13
]
©
2011 Elsevier Ltd.)
2 to 3. Obviously, in such a case, the expressions for the currents I
x
and I
z
change as
follows:
V
0
R
1
and
I
z
¼
V
0
V
in
I
x
¼
ð
15
:
39
Þ
R
2
The transfer characteristics for the CCW mode can be explained similar to the case
of CW mode [
14
] which is omitted to conserve the space. The expressions of two
threshold voltages in this case are given by:
1
V
0
1
V
0
R
2
R
1
R
2
R
1
V
TH
¼
;
and
V
TL
¼
ð
15
:
40
Þ
A voltage controlled bistable multivibrator is obtained by connecting an external
voltage source V
B
at the Y
2
terminal of the DVCC as shown in Fig.
15.10
. With the
introduction of additional controlled voltage it is obvious that the threshold voltages
in both CW and CCWmodes will become a function of this control voltage also. By
routine analysis, the modified expressions for the threshold voltages determined by
the following expressions
In CW mode:
V
0
V
0
R
1
R
2
R
1
R
2
V
TH
¼
1
V
B
;
and
V
TL
¼
1
V
B
ð
15
:
41
Þ
and in CCW mode:
1
V
0
þ
V
B
;
1
V
0
þ
V
B
R
2
R
1
R
2
R
1
R
2
R
1
R
2
R
1
V
TH
¼
and
V
TL
¼
ð
15
:
42
Þ
The effectiveness of the above bistable multivibrators have been confirmed by
implementing the DVCC by AD844AN ICs and from the breadboard prototypes
the operating frequency of the proposed bistable circuits was found to be around
500 KHz.
Search WWH ::
Custom Search