AD632 Data Sheet
Rev. D | Page 8 of 12
OPERATION AS A MULTIPLIER
Figure 7 shows the basic connection for multiplication. Note
that the circuit meets all specifications without trimming.
Figure 7. Basic Multiplier Connection
When needed, the user can reduce ac feedthrough to a minimum
(as in a suppressed carrier modulator) by applying an external
trim voltage (±30 mV range required) to the X or Y input. Figure 4
shows the typical ac feedthrough with this adjustment mode.
Note that the feedthrough of the Y input is a factor of 10 lower
than that of the X input and is to be used for applications where
null suppression is critical.
The Z
2
terminal of the AD632 can be used to sum an additional
signal into the output. In this mode, the output amplifier behaves
as a voltage follower with a 1 MHz small signal bandwidth and
a 20 V/μs slew rate. Always reference this terminal to the ground
point of the driven system, particularly if this is remote. Like-
wise, reference the differential inputs to their respective signal
common potentials to realize the full accuracy of the AD632.
A much lower scaling voltage can be achieved without any reduc-
tion of input signal range using a feedback attenuator, as shown
in Figure 8. In this example, the scale is such that V
OUT
= XY, so
that the circuit can exhibit a maximum gain of 10. This connection
results in a reduction of bandwidth to about 80 kHz without the
peaking capacitor, C
F
. In addition, the output offset voltage is
increased by a factor of 10 making external adjustments necessary
in some applications.
Feedback attenuation also retains the capability for adding a
signal to the output. Signals can be applied to the Z terminal,
where they are amplified by −10, or to the common ground
connection where they are amplified by −1. Input signals can
also be applied to the lower end of the 2.7 kΩ resistor, giving a
gain of +9.
Figure 8. Connections for Scale Factor of Unity
X
1
+V
S
X
2
V
OS
OUT
Z
1
Z
2
Y
1
Y
2
–V
S
–15V
+15V
X INPUT
±10V FS
±12V PK
Y INPUT
±10V FS
±12V PK
OUTPUT, ±12V PK
(X
1
– X
2
) (Y
1
– Y
2
)
OPTIONAL SUMMIN
INPUT, Z, ±10V PK;
V
OS
TERMINAL
NOT USED
10
+ Z
2
=
09040-008
X
1
+V
S
X
2
OUT
Z
1
Z
2
V
OS
Y
1
Y
2
–V
S
–15V
+15V
X INPUT
±10V FS
±12V PK
Y INPUT
±10V FS
±12V PK
OUTPUT, ±12V PK
= (X
1
– X
2
) (Y
1
– Y
2
)
(SCALE = 1)
09040-009
