AN6077 INTERSIL [Intersil Corporation], AN6077 Datasheet - Page 3

• Manufacturer Part Number: AN6077
• Description: An IC Operational Transconductance Amplifier With Power Capability
• Manufacturer: INTERSIL [Intersil Corporation]

Transistors from CA3046 array.
AGC System with extended input range.
Horizontal: 25mV/Div. Vertical: 50 A/Div., I
Simplified Differential Input to Single Ended
Output Conversion
One of the more exacting configurations for operational
amplifiers is the differential to single-ended conversion
circuit. Figure 10 shows some of the basic circuits that are
usually employed. The ratios of the resistors must be
precisely matched to assure the desired common mode
rejection. Figure 11 shows another system using the
CA3080 to obtain this conversion without the use of
precision resistors. Differential input signals must be kept
under 126mV for better than 5 percent nonlinearity. The
FIGURE 6. A CIRCUIT SHOWING HOW THE SIGNAL
FIGURE 8. CA3080 TRANSFER CHARACTERISTIC FOR THE
E
IN
51
2K
2K
HANDLING CAPABILITY OF THE CIRCUIT OF
FIGURE 4 CAN BE EXTENDED THROUGH THE
CONNECTION OF DIODES ON THE INPUT
CIRCUIT OF FIGURE 4
2
4
11
1
3
5
8
7
9
6
12
4-3
2
3
CA3080A
14
13
V-
DIODE
CURRENT
ABC
= 100 A
+
6
10K
Application Note 6077
E
O
Horizontal: 0.5V/Div. Vertical: 50 A/Div., I
Diode Current = 1mA
common mode range is that of the CA3080 differential
amplifier. In addition, the gain characteristic follows the
standard differential amplifier g
-0.3%/
provide the precise gain control obtained with the standard
operational amplifier approach, it does provide a good
simple compromise suitable for many differential transducer
amplifier applications.
FIGURE 7. TOTAL SYSTEM GAIN vs AMPLIFIER BIAS
FIGURE 9. CA3080 TRANSFER CHARACTERISTIC FOR THE
0.01
100
1.0
0.1
10
o
0
C. Although the system of Figure 11 does not
100
CURRENT FOR SEVERAL VALUES OF DIODE
CURRENT
CIRCUIT OF FIGURE 6
200
300
I
ABC
m
( A)
temperature coefficient of
400
ABC
500
= 100 A,
0mA
10 A
100 A
0.5mA
1mA
DIODE
CURRENT