Datasheet AD632 (Analog Devices) - 8

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AD632 Data Sheet OPERATION AS A MULTIPLIER
Figure 7 shows the basic connection for multiplication. Note A much lower scaling voltage can be achieved without any reduc- that the circuit meets all specifications without trimming. tion of input signal range using a feedback attenuator, as shown in Figure 8. In this example, the scale is such that VOUT = XY, so
X +15V
that the circuit can exhibit a maximum gain of 10. This connection
X INPUT 1 +VS ±10V FS
results in a reduction of bandwidth to about 80 kHz without the
±12V PK X2
peaking capacitor, CF. In addition, the output offset voltage is
OUTPUT, ±12V PK OUT (X1 – X2) (Y1 – Y2) = + Z
increased by a factor of 10 making external adjustments necessary
2 10
in some applications.
VOS Z1 OPTIONAL SUMMING
Feedback attenuation also retains the capability for adding a
Z2 INPUT, Z, ±10V PK; VOS TERMINAL
signal to the output. Signals can be applied to the Z terminal,
Y NOT USED Y INPUT 1
where they are amplified by −10, or to the common ground
±10V FS ±12V PK Y
8
2 –VS –15V
00 connection where they are amplified by −1. Input signals can 0- 04 09 also be applied to the lower end of the 2.7 kΩ resistor, giving a Figure 7. Basic Multiplier Connection gain of +9. When needed, the user can reduce ac feedthrough to a minimum (as in a suppressed carrier modulator) by applying an external
X1 +VS +15V X INPUT ±10V FS
trim voltage (±30 mV range required) to the X or Y input. Figure 4
±12V PK X2
shows the typical ac feedthrough with this adjustment mode.
OUTPUT, ±12V PK OUT = (X1 – X2) (Y1 – Y2)
Note that the feedthrough of the Y input is a factor of 10 lower
(SCALE = 1)
than that of the X input and is to be used for applications where
Z1
null suppression is critical.
Z2
The Z2 terminal of the AD632 can be used to sum an additional
Y V Y INPUT 1 OS
signal into the output. In this mode, the output amplifier behaves
±10V FS ±12V PK Y
9 as a voltage follower with a 1 MHz small signal bandwidth and
2 –VS –15V
00 0- 04 a 20 V/μs slew rate. Always reference this terminal to the ground 09 point of the driven system, particularly if this is remote. Like- Figure 8. Connections for Scale Factor of Unity wise, reference the differential inputs to their respective signal common potentials to realize the full accuracy of the AD632. Rev. D | Page 8 of 12 Document Outline Features Applications Functional Block Diagram General Description Product Highlights Revision History Specifications Absolute Maximum Ratings Thermal Resistance Pin Configurations and Function Descriptions Typical Performance Characteristics Operation As a Multiplier Operation As a Divider Outline Dimensions Ordering Guide