MC1494P ONSEMI [ON Semiconductor], MC1494P Datasheet - Page 12

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

amplifier. The amplifier can handle 1.0 Vrms and exhibits a
gain of approximately 20 dB. It is AGC’d through a 60 dB
dynamic range with the application of an AGC voltage from
0 Vdc to 1.0 Vdc. The bandwidth of the amplifier is
determined by the load resistor and output stray capacitance.
For this reason, an emitter–follower buffer has been added to
extend the bandwidth in excess of 1.0 MHz.
Balanced Modulator
resulting output is suppressed–carrier double–sideband
modulation. In terms of sinusoidal inputs, this can be seen in
the following equation:
e in
V AGC
12
The circuit of Figure 26 demonstrates the linear AGC
When two–time variant signals are used as inputs, the
Figure 26. Wideband Amplifier with Linear AGC
R
10
9
16 k
11
+
+
1
3.0 k
12
3
10 pF
510
6
7
MC1494
6.2 k
13
0.1 F
8
10
9
4
–15 V +15 V
11
+
+
5 15 13
–15 V +15 V
51 k
20 k
20 k
5
30 k
P2
P1
12
MC1494
15
2
or Equivalent
51 k
14
4
(2N3904)
Figure 25. Square Root Circuit
2N3946
0.1 F
7
P3 20 k
P2 20 k
62 k
51 k
–15 V
8
2
3.0 k
e o
MC1494
14
6
1
3
16 k
where m is the modulation frequency and c is the carrier
frequency. This equation can be expanded to show the
suppressed carrier or balanced modulation:
nature, the modulation which takes place when using the
MC1494 is linear. This means that for two sinusoidal inputs,
the output will contain only two frequencies, the sum and
difference, as seen in the above equation. There will be no
spectrum centered about the second harmonic of the carrier,
or any multiple of the carrier. For this reason, the filter
requirements of a modulation system are reduced to the
minimum. Figure 27 shows the MC1494 configuration to
perform this function.
been modified. This has been done primarily to increase the
bandwidth by lowering the output impedance of the MC1494
and then lowering R X and R Y to achieve a gain of 1. The e c
can be as large as 1.0 V peak and e m as high as 2.0 V peak.
No output offset adjust is employed since we are interested
only in the AC output components.
the multiplier inputs as well as provide matching input
impedance. The output frequency range of this configuration
is determined by the 4.7 k output impedance and capacitive
loading. Assuming a 6.0 pF load, the small–signal bandwidth
is 5.5 MHz.
rejection of
50 k
Unlike many modulation schemes, which are nonlinear in
Notice that the resistor values for R X , R Y and R L have
The input reisstors (R) are used to supply bias current to
The circuit of Figure 27 will provide at typical carrier
P4
2
3
V O =
–
MC1741C
+
+15 V –15 V
V O = K ( e 1 cos m t) (e 2 cos c t)
R L
7
10pF
70 dB from 10 kHz to 1.5 MHz.
Ke 1 e 2
22 k
2
MOTOROLA ANALOG IC DEVICE DATA
4
6
–10 V < V Z < 0 V
[cos( c + m t
V Z
V O
V O = 10 |V Z |
(1N5241B)
Equivalent
1N962B
(11V)
or
cos c
m )t]