OPA623AP BURR-BROWN [Burr-Brown Corporation], OPA623AP Datasheet - Page 12

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

CIRCUIT LAYOUT
The high-frequency performance of the operational ampli-
fier OPA623 can be greatly affected by the physical layout
of the printed circuit board. The following tips are offered as
suggestions. Oscillations, ringing, poor bandwidth and set-
tling, and peaking are all typical problems that plague high-
speed components when they are used incorrectly.
• A resistor (100 to 250 ) in series and close to the high-
• Bypass power supplies very close to the device pins. Use
• PC board traces for power lines should be wide to reduce
FIGURE 10. Circuit Schematic for Non-inverting and Inverting Configuration. Refer to Table I for Resistor Values.
TABLE I. Recommended Component Values.
COMPONENT
R
R
R
R
R
Typical
Bandwidth (MHz)
i
1
2
N1
N2
V
V
impedance, noninverting input is necessary to reduce
peaking; this resistor prevents any very high-frequency
oscillations at the op amp input, which can lead to an
excessive increase in quiescent current.
tantalum chip capacitors (approximately 2.2 F) with a
parallel 470pF ceramic chip capacitor. Surface-mount
types are recommended because of their low lead induc-
tance. Although the OPA623 operates at a low quiescent
current, high charging and discharging currents flow
during steep transitions.
impedance and inductance.
OUT
OUT
= 0.2Vp-p
= 2.8Vp-p
®
OPA623
150
390
200
In–
68
330
200
–2
—
In+
150
390
390
56
360
–1
—
—
R
N2
R
50
N1
R
3
200
360
320
340
+1
R
R
—
—
—
OPA623AP
i
i
3
2
3
2
GAIN
R
OPA623
OPA623
2
180
300
300
290
350
+2
R
R
—
—
7
4
7
4
1
1
Non Inverting
6
6
Inverting
100
300
75
260
+5
—
—
—
12
50
50
R
R
100
130
15
• Make short low-inductance traces. The entire physical
• Use a low-impedance ground plane on the component
• Sockets are not recommended because they add signifi-
• Use low-inductance, surface-mounted components. Cir-
• Plug-in prototype boards and wire-wrap boards will not
• Make the feedback trace as short as possible. The invert-
+10
170
210
O
O
—
—
circuit should be as small as possible.
side to ensure that low-impedance ground is available
throughout the layout, however, do not extend the ground
plane under high-impedance nodes such as the amplifier’s
input terminals, which are sensitive to stray capacitances.
cant inductance and parasitic capacitance.
cuits using all surface-mount components with the
OPA623AU will offer the best AC performance.
function well. A clean layout using RF techniques is
essential—there are no shortcuts.
ing input is sensitive to stray capacitances that lead to
peaking in the frequency response. A stray capacitance at
the inverting input increases the gain at high frequencies.
Gnd
150
390
200
+5V
–5V
68
200
330
–2
—
Out
Out
150
390
390
56
360
–1
—
—
C1
470pF
C2
470pF
270
470
320
340
OPA623AU
+1
—
—
—
C3
10nF
C4
10nF
GAIN
180
300
300
290
350
+2
—
—
C5
2.2µF
C6
2.2µF
7
4
100
300
76
260
+5
—
—
—
100
160
18
+10
170
210
—
—