OPA622AP BURR-BROWN [Burr-Brown Corporation], OPA622AP Datasheet - Page 11

• Manufacturer Part Number: OPA622AP
• Description: Wide-Bandwidth OPERATIONAL AMPLIFIER
• Manufacturer: BURR-BROWN [Burr-Brown Corporation]

Application circuits generally do not show the resistor
R
With a fixed R
perature (see Typical Performance Curves.) This variation
of the quiescent current with temperature keeps the band-
width and AC behavior relatively constant with temperature.
It is also possible to vary the quiescent current by an external
control signal or circuitry. Figure 3 shows a circuit to disable
the OPA622 with TTL-compatible logic levels. 0V/5V logic
levels are converted into a 1mA/0mA current connected to
Pin 2. The current flowing in R
2 to approximately 1V above the –V
to near zero and disabling the OPA622.
OTA AND OUTPUT BUFFER SECTIONS
An Operational Transconductance Amplifier (OTA) and an
output buffer are the basic building blocks of a current-
feedback amplifier. The current-feedback configuration of
the OPA622 is illustrated in Figure 4. The OTA consists of
a complementary emitter follower and a subsequent comple-
mentary current mirror. The voltage at the high-impedance
+In terminal is transferred to the BUF+ input/output termi-
nal at a low impedance. If a current flows into or out of the
BUF+ terminal, the complementary mirror reflects the
current to the OTA terminal. The current flow at the high-
impedance OTA terminal is determined by the product of
the voltage between the +In and BUF+ terminals and the
transconductance. The output buffer section is an open-loop
buffer consisting of complementary emitter followers. It is
designed to drive cables or low-impedance loads. The buffer
output is not current-limited or -protected. As can be seen in
Figure 4, the feedback network for a current-feedback
amplifier is applied between the V
Figure 8 illustrates the bandwidth for various output volt-
ages of the current feedback configuration.
FIGURE 4. Current-Feedback Amplifier.
Q
, but it is required for proper operation.
Q
, the quiescent current increases with tem-
+V
–V
+In
12
5
CC
CC
4
Q
increases the voltage at Pin
OUT
CC
OTA
and BUF+ terminals.
rail, thus reducing I
C
OTA
BUF+
13
Q
11
10
R
FIGURE 3. Logic-Controlled Disable Circuit.
FEEDBACK BUFFER SECTION
This section of the OPA622 is a complementary emitter
follower identical to the input buffer of the OTA section. It
is designed for interstage buffering, not for driving long
cables or low-impedance loads. A minimum load resistance
of 500 is recommended when using the feedback buffer as
a stand-alone device. The feedback buffer output is not
current-limited or -protected. The bandwidth of the feedback
buffer is shown in Figure 7.
1
5V: OPA622 On
Logic In
+ V
0/5V
–V
11
I
I
OB
CC OUT
CC OUT
C
C
6
= 0:
= 1mA: OPA622 Off
I
C
9
+5V
OPA622 On
2N2907
4.7k
R
2
OPA622
2
Current Source
100
430
R
Circuitry
Internal
100k
Q
–5V
V
OUT
5
OPA622
®