MPY634AM BURR-BROWN [Burr-Brown Corporation], MPY634AM Datasheet - Page 6

• Manufacturer Part Number: MPY634AM
• Description: Wide Bandwidth PRECISION ANALOG MULTIPLIER
• Manufacturer: BURR-BROWN [Burr-Brown Corporation]

Internal device tolerances make this relationship accurate to
within approximately 25%. Some applications can benefit
from reduction of the SF by this technique. The reduced
input bias current, noise, and drift achieved by this technique
can be likened to operating the input circuitry in a higher
gain, thus reducing output contributions to these effects.
Adjustment of the scale factor does not affect bandwidth.
The MPY634 is fully characterized at V
operation is possible down to 8V with an attendant reduc-
tion of input and output range capability. Operation at
voltages greater than 15V allows greater output swing to be
achieved by using an output feedback attenuator (Figure 1).
As with any wide bandwidth circuit, the power supplies
should be bypassed with high frequency ceramic capacitors.
These capacitors should be located as near as practical to the
power supply connections of the MPY634. Improper by-
passing can lead to instability, overshoot, and ringing in the
output.
FIGURE 1. Connections for Scale-Factor of Unity.
BASIC MULTIPLIER CONNECTION
Figure 2 shows the basic connection as a multiplier. Accu-
racy is fully specified without any additional user-trimming
circuitry. Some applications can benefit from trimming of
one or more of the inputs. The fully differential inputs
facilitate referencing the input quantities to the source volt-
age common terminal for maximum accuracy. They also
allow use of simple offset voltage trimming circuitry as
shown on the X input.
The differential Z input allows an offset to be summed in
V
the output voltage ground reference and should be connected
to the ground of the driven system for maximum accuracy.
A method of changing (lowering) SF by connecting to the
SF pin was discussed previously. Figure 1 shows an alterna-
tive method of changing the effective SF of the overall
circuit by using an attenuator in the feedback connection to
Z
and is thus accompanied by a reduction in bandwidth and an
1
OUT
. This method puts the output amplifier in a higher gain
X Input
±10V FS
±12V PK
Y Input
±10V FS
±12V PK
. In basic multiplier operation, the Z
®
R
SF
X
X
SF
Y
Y
MPY634
1
2
1
2
MPY634
= 5.4k
+V
–V
Out
Z
Z
S
S
1
2
10 – SF
+15V
–15V
SF
10k
V
= (X
(Scale = 1V)
OUT
2
1
90k
, ±12V PK
S
– X
input serves as
=
2
) (Y
C
Capacitor
Optional
Peaking
F
1
= 200pF
15V but
– Y
2
)
6
FIGURE 2. Basic Multiplier Connection.
increase in output offset voltage. The larger output offset
may be reduced by applying a trimming voltage to the high
impedance input, Z
The flexibility of the differential Z inputs allows direct
conversion of the output quantity to a current. Figure 3
shows the output voltage differentially-sensed across a se-
ries resistor forcing an output-controlled current. Addition
of a capacitor load then creates a time integration function
useful in a variety of applications such as power computa-
tion.
SQUARER CIRCUIT (FREQUENCY DOUBLER)
Squarer, or frequency doubler, operation is achieved by
paralleling the X and Y inputs of the standard multiplier
circuit. Inverted output can be achieved by reversing the
differential input terminals of either the X or Y input.
Accuracy in the squaring mode is typically a factor of two
better than the specified multiplier mode with maximum
error occurring with small (less than 1V) inputs. Better
accuracy can be achieved for small input voltage levels by
reducing the scale factor, SF.
DIVIDER OPERATION
The MPY634 can be configured as a divider as shown in
Figure 4. High impedance differential inputs for the numera-
tor and denominator are achieved at the Z and X inputs,
Hello
Optional Offset
FIGURE 3. Conversion of Output to Current.
50k
Trim Circuit
X Input
±10V FS
±12V PK
Y Input
±10V FS
±12V PK
+15V
–15V
470k
X Input
±10V FS
±12V PK
Y Input
±10V FS
±12V PK
X
X
SF
Y
Y
1
2
1
2
MPY634
1k
2
.
+V
–V
Out
Z
Z
S
1
2
S
X
X
SF
Y
Y
1
2
1
2
MPY634
+15V
–15V
+V
–V
Out
I
(X
OUT
Z
Z
S
S
1
1
2
– X
=
10V
2
Resistor,
) (Y
Sensing
R
Current
=
S
min
, 2k
(X
V
1
OUT
+15V
1
–15V
– Y
– X
, ±12V PK
2
)
2
10V
) (Y
x
Z, ±10V PK
R
Summing
1
1
Optional
S
Integrator
Capacitor
(see text)
– Y
Input,
2
)
+ Z
2