OPA623AP BURR-BROWN [Burr-Brown Corporation], OPA623AP Datasheet - Page 9

• Manufacturer Part Number: OPA623AP
• Description: Wide Bandwidth, Current-Feedback OPERATIONAL AMPLIFIER
• Manufacturer: BURR-BROWN [Burr-Brown Corporation]

DISCUSSION OF
PERFORMANCE
Requiring very low quiescent power, the OPA623 achieves
its exceptional AC performance by using the current-feed-
back topology. This wide-band monolithic operational am-
plifier is designed for gain applications of up to 20V/V,
where power and cost are of primary concern.
Operating from a 5V supply, the OPA623 consumes only
40mW, yet maintains a 350MHz large-signal bandwidth at
V
from the current-feedback architecture, the OPA623 offers
stable operation with no compensation capacitor, even at
unity gain.
With its low differential gain and phase errors of typically
0.12% and 0.05 at 4.43MHz, the OPA623 meets the perfor-
mance and cost requirements of high-volume broadcast and
HDTV applications.
The OPA623’s large-signal bandwidth, high slew rate,
excellent pulse response, and high drive capabilities are
features well-suited to wide-band RGB video applica-
tions, RF instruments, and even high-speed digital com-
munication systems.
FIGURE 2. Simplified Circuit Diagram.
OUT
= 2.8Vp-p and a 2100V/ s slew rate. Benefiting
Circuitry
Bias
+In
3
OTA
2
–In
9
For most circuit configurations, the OPA623 current-
feedback op amp can be treated like a conventional op
amp. As with a voltage-feedback op amp, the feedback
network connected to the inverting input controls the
closed-loop gain. But with a current-feedback op amp, the
impedance of the feedback network also controls the
open-loop gain and frequency response. Feedback resis-
tor values can be selected to provide nearly constant
closed-loop bandwidth over a wide range of gains and flat
gain adjustment vs frequency.
DESCRIPTION
A wide-band operational transconductance amplifier (OTA)
and an output buffer are the main blocks of a current-
feedback op amp. The simplified circuit diagram is illus-
trated in Figure 2. The OTA consists of a complementary
unity-gain amplifier and a subsequent current mirror. The
input buffer is connected across the inputs of the op amp.
The voltage at the high-impedance +In terminal is trans-
ferred to the –In terminal at a low impedance. The current
mirrors reflect any current flowing into or out of the +In
terminal by a fixed ratio to the high-impedance OTA output,
which is directly connected to the complementary output
buffer. It is designed to drive low-impedance transmission
BUFFER
–V
+V
CC
CC
= –5V
= +5V
4
7
6
V
OPA623
OUT
®