MC1494P ONSEMI [ON Semiconductor], MC1494P Datasheet - Page 11

• Manufacturer Part Number: MC1494P
• Description: LINEAR FOUR-QUADRANT MULTIPLIER INTEGRATED CIRCUIT
• Manufacturer: ONSEMI [ON Semiconductor]

loop (thus making it more practical on a production basis), is:
1.
2.
3.
4.
5.
accuracy to be expected decreases in direct proportion to the
denominator voltage. As a result, if V X is set to 10 V and
0.5% accuracy is available, then 5% accuracy can be
expected when V X is only 1.0 V.
one polarity (positive) while V Z may be either polarity.
Square Root
to the multiplier are connected together results in the square
root function as indicated in Figure 24. This circuit too may
MOTOROLA ANALOG IC DEVICE DATA
A simpler approach, since it does not involve breaking the
Users of the divide circuit should be aware that the
In accordance with an earlier statement, V X may have only
A special case of the divide circuit in which the two inputs
Set V Z = 0 V and adjust the output offset potentiometer
(P3) until the output voltage (V O ) remains at some (not
necessarily zero) constant value as V X is varied
between +1.0 V and +10 V.
Maintain V Z at 0 V, set V X at +10 V and adjust the
Y input offset potentiometer (P1) until V O = 0 V.
With V X = V Z , adjust the X input offset potentiometer
(P2) until the output voltage remains at some (not
necessarily –10 V) constant value as V Z = V X is varied
between +1.0 V and +10 V.
Maintain V X = V Z and adjust the scale factor
–10 V as V Z = V X is varied between +1.0 V and +10 V.
Repeat steps 1 through 4 as necessary to achieve
optimum performance.
potentiometer (R L ) until the average value of V O is
V Z
Figure 24. Basic Square Root Circuit
+
KV O 2
V X
10 pF
10 pF
–
510
510
–
+
MC1494
10
9
X
+
11
–15 V +15 V
+
+
5
+
15 13
30 k
12
MC1494
4
V O =
KV O 2 = –V Z
7
P1 20 k
P3 50 k
P2 20 k
V O
62 k
or
Figure 23. Practical Divide Circuit
V Z 0 V
|V Z |
K
8
2
14
3
1
6
MC1494
16 k
suffer from latch–up problems similar to those of the divide
circuit. Note that only one polarity of input is allowed and
diode clamping (see Figure 25) protects against accidental
latch–up.
This circuit too, may be adjusted in the closed–loop mode:
1.
2.
3.
4.
NOTE: Operation near 0 V input may prove very inaccurate,
hence, it may not be possible to adjust V O to zero but rather
only to within 100 mV to 400 mV of zero.
AC APPLICATIONS
Wideband Amplifier with Linear AGC
voltage is applied to the other input, the amplitude of the
output signal can be controlled in a linear fashion by varying
the DC voltage. Hence, the multiplier can function as a DC
coupled, wideband amplifier with linear AGC control.
multiplier has three other distinct advantages over most other
types of AGC systems. First, the AGC dynamic range is
theoretically infinite. This stems from the basic fact that with
0 Vdc applied to the AGC, the output will be zero regardless
of the input. In practice, the dynamic range is limited by the
ability to adjust the input offset adjust potentiometers. By
using cermet multi–turn potentiometers, a dynamic range of
80 dB can be obtained. The second advantage of the
multiplier is that variation of the AGC voltage has no effect on
the signal handling capability of the signal port, nor does it
alter the input impedance of the signal port. This feature is
particularly important in AGC systems which are phase
sensitive. A third advantage of the multiplier is that the output
voltage swing capability and output impedance are
unchanged with variations in AGC voltage.
50 k
If one input to the MC1494 is a DC voltage and a signal
In addition to the advantage of linear AGC control, the
Set V Z = –0.01 Vdc and adjust P3 (output offset) for
V O = 0.316 Vdc.
Set V Z to –0.9 Vdc and adjust P2 (“X” adjust) for
V O = +3.0 Vdc.
Set V Z to –10 Vdc and adjust P4 (gain adjust) for
V O = +10 Vdc.
Steps 1 through 3 may be repeated as necessary to
achieve desired accuracy.
2
3
MC1741CP1
–
+
R L
+15 V
10 pF
7
22 k
–15 V
4
6
–10 V V Z +10 V
0 < V X < +10 V
V Z
V O
V O =
–10 V Z
Equivalent
1N5240A
V X
(10 V)
or
11