ca3280 Intersil Corporation, ca3280 Datasheet - Page 6

• Manufacturer Part Number: ca3280
• Description: Dual, 9mhz, Operational Transconductance Amplifier Ota
• Manufacturer: Intersil Corporation

of the CA3280. The linearization diode impedance also
decreases as the diode bias current increases, which further
loads the input. The diodes, in addition to acting as a
linearization network, also operate as an additional
attenuation system to accommodate input signals in the volt
range when they are applied through appropriate input
resistors.
FIGURE 6. DIFFERENTIAL TO SINGLE ENDED CONVERTER
FIGURE 4. VOA SHOWING LINEARIZATION DIODES AND
DIFFERENTIAL
INPUT
CURRENT DRIVE
2k
2k
V+
I
D
16
15
1/2
CA3280
+
14
-
1
R
R
V-
D
D
6
= SMALL SIGNAL DIODE
I
3
4
D
IMPEDANCE
52
(mA) x 1.34 =
+15V
68k
-15V
13
VOA
I
ABC
70
I
D
10k
SINGLE-
ENDED
OUTPUT
CA3280, CA3280A
Figure 10 shows a triangle wave to sine wave converter
using the CA3280. Two 100k resistors are connected
between the differential amplifier emitters and V+ to reduce
the current flow through the differential amplifier. This allows
the amplifier to fully cut off during peak input signal
excursions. THD is appropriately 0.37% for this circuit.
FIGURE 5. BLOCK DIAGRAM OF LINEARIZED VOA
100k
FIGURE 7. TYPICAL GAIN CONTROL CIRCUIT
V+
600
V-
10V
INPUT
330k
10k
P-P
10k
16
15
68k
20k
CONTROL
VOLTAGE
R
I
D
1/2
CA3280
+
D
-
1
3
VOA
I
ABC
14
4
V- = -15V
13
V+ = +15V
OUTPUT
21V
14mV AGC
FEEDTHRU
400 V
NOISE AT
MAX GAIN
P-P
15k