Datasheet

REV. E
AD633
–5–
0.1␮F
+15V
E
W =
E
2
10V
8
7
6
5
1
2
3
4
AD633JN
0.1␮F
X1
X2
Y1
Y2
–V
S
+V
S
W
Z
–15V
C
R
R1
1k⍀
R2
3k⍀
Figure 5. ”Bounceless” Frequency Doubler
At ω
o
= 1/CR, the X input leads the input signal by 45° (and is
attenuated by √2), and the Y input lags the X input by 45° (and
is also attenuated by √2). Since the X and Y inputs are 90° out of
phase, the response of the circuit will be (satisfying Equation 3):
W
V
E
t
E
t
E
V
t
oo
o
=
()
+°
()
−°
()
=
()
()
1
10
2
45
2
45
40
2
2
sin sin
sin
ωω
ω
(4)
which has no dc component. Resistors R1 and R2 are included to
restore the output amplitude to 10 V for an input amplitude of 10 V.
The amplitude of the output is only a weak function of frequency:
the output amplitude will be 0.5% too low at ω = 0.9 ω
o
, and
ω
o
= 1.1 ω
o
.
Generating Inverse Functions
Inverse functions of multiplication, such as division and square
rooting, can be implemented by placing a multiplier in the feed-
back loop of an op amp. Figure 6 shows how to implement a
square rooter with the transfer function
WEV=
()
10
(5)
for the condition E < 0.
0.1␮F
+15V
8
7
6
5
1
2
3
4
AD633JN
0.1␮F
X1
X2
Y1
Y2
–V
S
+V
S
W
Z
–15V
10E
W =
()
V
0.1␮F
0.1␮F
+15V
–15V
OP27
7
4
E
1N4148
1N4148
Figure 6. Connections for Square Rooting
0.1␮F
+15V
E
8
7
6
5
1
2
3
4
AD633JN
0.1␮F
X1
X2
Y1
Y2
–V
S
+V
S
W
Z
–15V
W' = –10V
E
E
X
0.1␮F
0.1␮F
R
10k⍀
R
10k⍀
+15V
–15V
E
X
AD711
Figure 7. Connections for Division
Likewise, Figure 7 shows how to implement a divider using a
multiplier in a feedback loop. The transfer function for the
divider is
WV
E
E
X
' =−
()
10
(6)
0.1␮F
+15V
8
7
6
5
1
2
3
4
AD633JN
0.1␮F
X1
X2
Y1
Y2
–V
S
+V
S
W
Z
–15V
R1
R2
W =
(X
1
– X
2
) (Y
1
– Y
2
)
+ S
10V
X
INPUT
Y
INPUT
(R1 + R2)
R1
1k⍀ R1, R2 100k⍀
S
Figure 8. Connections for Variable Scale Factor
Variable Scale Factor
In some instances, it may be desirable to use a scaling voltage
other than 10 V. The connections shown in Figure 8 increase
the gain of the system by the ratio (R1 + R2)/R1. This ratio is
limited to 100 in practical applications. The summing input, S,
may be used to add an additional signal to the output or it may
be grounded.
Current Output
The AD633’s voltage output can be converted to a current
output by the addition of a resistor R between the AD633’s W
and Z pins as shown in Figure 9. This arrangement forms
(X
1
– X
2
) (Y
1
– Y
2
)
10V
1
R
I
O
=
X
INPUT
0.1␮F
+15V
–15V
8
7
6
5
1
2
3
4
AD633JN
0.1␮F
X1
X2
Y1
Y2
–V
S
+V
S
W
Z
Y
INPUT
1k⍀ R 100k⍀
R
Figure 9. Current Output Connections